Milking the Bodhi Tree: Mulberry for Disease Demons in Yōsai’s Record of Nourishing Life by Drinking Tea (Kissa yōjōki)

Abstract

In light of new discoveries of his writings, recent studies on the medieval Japanese monk Yōsai (or Eisai; 1141–1215) have moved away from longstanding preoccupations with his role in establishing Zen in Japan and instead stress his career-long orientation as an esoteric Buddhist monk of the Tendai school. Although these revisions have led to innovative readings of his promotion of tea in the first fascicle of his Record of Nourishing Life by Drinking Tea (Kissa yōjōki), similar approaches have yet to be attempted for the second fascicle of this well-known work, in which Yōsai argues for the apotropaic efficacy of mulberry against pathogenic demons. In this article, I seek to remedy this gap firstly by situating Yōsai’s healing program within broader contemporary trends in esoteric ritual healing. Examining the place of mulberry across esoteric liturgical discourse reveals a rich semiotic network in which the tree was tied to three other key ritual and medicinal materials: milkwood, milk, and the bodhi tree. In the second half of the article, I explore the ways that Yōsai’s argument for mulberry’s efficacy was shaped by an “exoteric” source, namely the biography of Śākyamuni Buddha. In this way, my analysis of the Kissa yōjōki provides insight into the interplay of “esoteric” and “exoteric” elements in Yōsai’s thought and career, even as attention to the specificity of his therapeutic claims for mulberry encourages us to move beyond sectarian frameworks.

1. Introduction

Among the works attributed to Yōsai 栄西 (also known as Eisai; 1141–1215), none has received as much popular and academic attention as his Record of Nourishing Life by Drinking Tea (Kissa yōjōki 喫茶養生記).1 Until recently, Yōsai’s work has been treated as a prime mover in the revival of tea drinking in Japan in the Kamakura period (1185–1333). Thought to have introduced the style of drinking powdered tea (maccha 抹茶) from Song-period China (960–1279), his record has been seen as a precursor to the formalized tea ceremony (chanoyu 茶湯 or sadō 茶道) that would eventually develop in the Muromachi era (1336–1573).2 The role of the Kissa yōjōki in this narrative rests in turn upon a longstanding image of Yōsai in scholarship in the history of medieval Japanese Buddhism as the monk who introduced to Japan the Rinzai 臨済 (Ch. Linji) school of Zen, the form of Buddhism that has most often been associated with the tea arts of the late medieval period. In traditional historical accounts of the development of Buddhism from the Heian (794–1185) to the Kamakura periods, Yōsai was placed alongside Hōnen, Shinran, Dōgen, and Nichiren as one of the major figures of “Kamakura New Buddhism”, a broad movement seen as a reaction to, and departure from, the schools of “Old Buddhism”, Tendai 天台 and Shingon 真言. According to this account, the schools of Old Buddhism constituted corrupt monastic institutions with vast economic and political power closely tied to the aristocracy and imperial family. These schools focused on “esoteric teachings” (mikkyō 密教), in particular the performance of elaborate rituals aimed at magically safeguarding the lives and lineages of elite patrons. In contrast, the schools of Kamakura New Buddhism, organized around charismatic individuals with idiosyncratic and sometimes exclusivist teachings, promoted personal salvation and simple religious practices. These schools were said to usher in new forms of Buddhism that were much more accessible to a wider swath of the population than ever before in Japanese history.

The narrative of Kamakura New Buddhism was overturned in the mid-1970s by Kuroda Toshio 黒田俊雄 (1926–1993). Kuroda argued that the institutions of so-called “Old Buddhism”—better defined as kenmitsu 顕密 institutions, owing to their integration of both esoteric and exoteric (kengyō 顕教) teachings—continued to hold political power and to define religious orthodoxy into the Kamakura period and throughout the medieval era (Kuroda 1996; Abé 1999, pp. 399–428). The implications of Kuroda’s groundbreaking thesis are too many to recount here, suffice to say that recent research has indeed proven that the narrative of Kamakura New Buddhism falls short in helping us to make sense of the life of Yōsai and his Kissa yōjōki. Far from a radical reformer seeking to break away from the entrenched institutions of his day, Yōsai is more accurately seen as a careerist who made much of his experiences in Song China to receive official titles within mainstream ecclesiastical structures and promoted the protection of the state (Sueki 2008). Less of a preacher among the masses, he was highly skilled in temple administration and fund-raising projects, as can be seen in his formal role in the reconstruction of the major Nara 奈良 temple Tōdaiji 東大寺. Moreover, although a turn toward Zen doctrine can be evinced from the writings he produced after his return from his second trip to China in 1191, new discoveries of Yōsai’s writings at temples such as Shinpukuji 真福寺 (Nagoya city, Aichi) reflect the fact that for the majority of his career he was devoted to the doctrines and practices of esoteric Buddhism, specifically as they were understood in the Tendai school in which he was steeped (Mano 2011).3 Yōsai’s unfaltering orientation as a Taimitsu 台密 monk means that he saw theoretical congruence between esoteric and exoteric doctrines, especially the “Perfect Teaching” of the Lotus Sutra, even as his writings ultimately prioritize the former.4 Yōsai is even credited with his own esoteric lineage that continued after his death, known as the Yōjō-ryū 葉上流.

Besides the significance this shift in focus to Yōsai’s esoteric orientation holds for reassessing his thought and career as a whole (see, e.g., Mano 2014), this new perspective also provides a more insightful framework by which to understand what Yōsai sought to do in his Kissa yōjōki. Indeed, recent studies by Yoneda Mariko (Yoneda 2007, 2015), Iwama Machiko (Iwama 2009), and Edward Drott (2010) have elucidated important esoteric features of the work. Focusing primarily on the first fascicle, these studies have shown how Yōsai tethered the correlative system of Chinese medicine, organized around the “five viscera” (gozō 五臓), with that of the correlative system of the Indian Buddhist mandala, organized around the “five buddhas” (gobutsu 五仏).5 Yōsai dually prescribes the consumption of tea to strengthen the heart viscus, as a form of “external medicine”, and the contemplation of buddhas residing inside the body, as a kind of “internal medicine”.

Despite these important strides, a similar reevaluation has yet to be attempted for the second fascicle of the Kissa yōjōki. The reason is simply that this fascicle focuses on mulberry (kuwa 桑, often written 桒 in medieval sources; Morus alba), a plant material used as medicine that never garnered a level of fame comparable to that of tea. Even a very recent edited volume on the Kissa yōjōki devotes almost no attention to Yōsai’s promotion of mulberry as a therapeutic substance (Kumakura and Yao 2014). This oversight is curious when we consider the value given to Yōsai’s teachings on mulberry by Buddhists later in the medieval period. In his Keiran shūyōshū 渓嵐拾葉集, Kōshū 光宗 (1276–1350) records several secret transmissions he attributes to Yōsai’s esoteric Yōjō-ryū lineage; many of these teachings are related specifically to mulberry, such as the use of mulberry as a substitute for milk in ritual practice. Yōsai’s writings on mulberry also drew the attention of Zen monks as well. In his diary, Shaken nichiroku 蔗軒日録 (p. 153), Kikō Daishuku 季弘大叔 (1421–1487) refers to the Kissa yōjōki as the “Classic of Mulberry” (Sōkyō 桒経), an inexplicable reference in light of the largely tea-centered scholarship on the Kissa yōjōki. Before we can grasp why Yōsai’s writings on mulberry were so important for later Buddhists, we must examine the Kissa yōjōki with a question that has been asked many times already for tea: Why did Yōsai choose to promote mulberry instead of other therapeutic substances that were known in Japan at the time?

Long before Yōsai wrote his Kissa yōjōki, mulberry was a tree of great significance in Japan, owing most obviously to the indispensable role it plays in the ecology of sericulture. Because the leaves of Morus alba constitute the sole nutrition for the silkworm (kaiko 蚕), without which one cannot produce silk, mulberry trees were cultivated throughout Japan since prehistorical times (Coles 2019). In the ancient period, sericulture, together with weaving, was a key technology of the early state. Practiced by immigrant kinship groups versed in techniques developed in China, it figured prominently in ritual and myth, including legends surrounding silkworm and weaving goddesses that fed into the cults of major ancestral deities, such as Amaterasu 天照 (Como 2009). In this context, mulberry was often associated with immortality (Ibid., pp. 72–74). In fact, one poetic appellation for the Japanese archipelago was Fusō 扶桑 (Ch. Fusang; literally “Supporting Mulberries”), a term that referred to an isle inhabited by immortals and that was home to towering mulberry trees in the Daoist imagination (Pregadio 2008, vol. 2, pp. 788–90; Como 2009, p. 95). The cultivation of mulberry for sericultural purposes across the population continued into the medieval period (Amino 1997), and fields of mulberry would have been a common feature of the landscape, although little is known about enduring religious and ritual dimensions.

In the Kissa yōjōki, Yōsai claims that mulberry is a “medicine of immortality” (senyaku 仙薬), much as he does for tea. However, on the whole, his arguments for mulberry bear little resemblance to mythological images of the tree on the archipelago that circulated in the ancient period and have nothing to do with the lore or technology of sericulture. Neither, I argue, are they adequately explained by the personal experiences Yōsai acquired on his two trips to China, although his second trip, as we shall see, is an important part of the story. Rather, in this article, I suggest that Yōsai’s promotion of mulberry relates firstly to his role as an esoteric practitioner who was responding to salient trends of ritual healing in his day. In the first half of this article, a study of esoteric ritual discourse surrounding mulberry reveals a rich semiotic network in which the tree was tethered to three other materials important in ritual and medicine: “milkwood”, milk, and the bodhi tree.

Yet esoteric discourses only take us so far in grasping mulberry’s significance for Yōsai. In the second half, I turn to consider a narrative source that medieval Japanese monks would have deemed “exoteric”. In medieval Japan, the lines between exoteric teachings (kengyō) and esoteric teachings (mikkyō) were variably demarcated, and a significant amount of intellectual activity was devoted specifically to articulating how the doctrines found in these respective canons might be integrated. However, according to one fundamental distinction established early on in Japan by Kūkai 空海 (774–835), esoteric sutras were those preached by Dainichi Nyorai 大日如来 (Skt. Mahāvairocana), a transhistorical buddha understood as the ground of all reality and truth itself (Dharmakāya), whereas exoteric sutras were those preached by or focused on the historical figure of Śākyamuni Buddha (Abé 1999, pp. 129, 182).6 For medieval Tendai monks such as Yōsai, the category of exoteric teachings included everything from the most revered of the Mahāyāna sutras (i.e., Lotus Sutra) to the less profound “Tripiṭaka” (sanzōkyō 三蔵経) teachings designated as “Hīnayāna” (shōjō 小乗). One source classified within the latter, lower level of the exoteric teachings was the biography of Śākyamuni Buddha, told in “eight stages”. As we shall see, this biography was of much importance for Yōsai’s imagination of the efficacy of mulberry. In this way, Yōsai’s arguments in the Kissa yōjōki shed light on the interplay of esoteric and exoteric elements in his thought and career, even as they encourage us to move beyond this doctrinal binary.

2. Pharmaceutical Simplification in Early Medieval Ritual Healing

Although much of Yōsai’s Kissa yōjōki can be read in terms of his copious incorporation of Chinese writings on tea, and to a lesser extent his direct experiences in Song China, there is ample indication that the general focus of his work was informed by a broader shift in esoteric Buddhist ritual healing in Japan in his day. From the mid-Heian period, long before the young Yōsai would climb Mt. Hiei to study esoteric Buddhism, performances of the fire ceremony (goma 護摩) by esoteric monks had constituted an extravagant form of polypharmacy. Into the flames of the hearth at the center of the ritual altar, esoteric priests would toss a panoply of therapeutic and ritual materials, ranging from aromatics and medicinal substances to minerals, grains, oils, and woods. To manage knowledge about the diverse substances required for liturgical practice, compendia such as the Kōyōshō 香要抄 by Shingon monk Ken’i 兼意 (1072—after 1158) were compiled and circulated (Macomber 2020a). Yet over time—and especially during the late Heian and early Kamakura periods when Yōsai lived—monasteries found it increasingly difficult to maintain ample provisions of such materials, owing largely to the unreliability of trade through which most of these materials were imported from the continent (Kamikawa 2012, pp. 135–40). One indication of this trend can be seen in the shift in the field of esoteric ritual practice in this period from the “five-altar rite” (godan-hō 五檀法), which featured the orchestration of as many as five fire ceremony altars conducted by five priests simultaneously, sometimes in distant locations throughout the capital and its surrounding environs, to rituals with only a single altar (Hayami 1975, p. 89; Tomishima 1999).7 The profligate consumption of substances in elaborate ritual performances did not completely disappear at this time, but in many quarters of ritual practice, it gave way to a narrower focus on a smaller number of discrete potent substances.

One early example is “roasting poppy seeds” (keshiyaki 芥子焼), a goma ritual focused on Fudō Myōō 不動明王 in which poppy seeds, a demonifugic agent often used in rituals to exorcise spirits of the dead, were the only substances burned. Shinmura (1985, pp. 246–48) observes that over the Heian period “roasting poppy seeds” became one of the most popular esoteric rituals for healing. Another plant substance made the focal point of its own rite was willow (yanagi 柳). Addressed to the compassionate bodhisattva Kannon 観音, the rite was rooted in an earlier Chinese sutra entitled Scripture on the Dhāraṇī for Summoning the Bodhisattva Avalokiteśvara to Eradicate Toxic Harms (Ch. Qing Guanshiyin pusa xiaofu duhai tuolunizhou jing 請観世音菩薩消伏毒害陀羅尼呪経). This willow ritual was first transmitted by Taimitsu monks in the twelfth century, and they employed it, for example, against a deadly epidemic in 1156 (Hayami 2007, pp. 303–23).

Monks of the Jimon 寺門 lineage, a branch of Tendai located at Onjōji 園城寺, crafted at least two rituals with a single-substance focus. The first, known as “Expelling the Great Death Ritual” (jo daishi hō 除大死法), centered around Fudō for the elimination of epidemics. The botanical centerpiece of the ritual was “skeleton-path grass” (kotsurosō 骨路草), a type of milkwood (nyūboku 乳木).8 Milkwood refers to a type of unseasoned wood, many forms of which exude a milky w hite sap, more on which will be discussed later. In actual practice, skeleton-path grass, which was prescribed based on continental liturgies yet had an unclear identity, was substituted with karasuuri 烏瓜 (Trichosanthes cucumeroides), a vine native to Japan. The plant was also used in the Nyohō Sonshō 如法尊勝 ritual performed by Shingon monks on Mt. Kōya, a feature Youn-mi Kim (2013) points out was shared with the Uṣṇīṣavijayā dhāraṇī ritual performed in the Liao dynasty (907–1125) in China. Of greater historical consequence for the Jimon lineage was the second rite, the “Ritual for the Blue-faced Vajrayakṣa for Expelling Demons and Māras” (Shōshiki Daikongō Yasha byaku kima hō 青色大金剛藥叉辟鬼魔法). This ritual centered on moxibustion (kyū 灸), a healing modality in which dried mugwort (yomogi 蓬 or 艾) is burned on the patient’s skin. This ritual emerged in the early 1170s amidst anxieties over the rise of a previously unheard of affliction known as “corpse-vector disease” (denshibyō 傳屍病) (Macomber 2017, 2020b), which Jimon monks attributed to disease-causing demons.9

This trend toward pharmaceutical simplification in the field of esoteric ritual provides an important context for understanding Yōsai’s narrow focus on only two plant substances in the two fascicles of his Kissa yōjōki, tea and mulberry, respectively.10 There is some indication that Yōsai was directly aware of this trend. In numerous passages throughout the Kissa yōjōki, Yōsai emphasizes that his information about these materials is sourced from abroad (especially in the work’s second edition, the saijibon). However, it is notable that a substantial piece of his criticism of contemporary medical practice in Japan is directed at moxibustion specifically, which Yōsai argues causes “fire poison” (kadoku 火毒) and thus brings unwarranted iatrogenic harm (Mori 1999, pp. 344–45, 356–57). Moxibustion was practiced in the late twelfth century by a wide range of healers, including Buddhist hijiri 聖 and court physicians. Yet Yōsai likely understood that his closest competitors were those active in the field of esoteric ritual healing, such as monks belonging to the Jimon lineage, whom he may have known created an unusual ritual centered on moxibustion. That Yōsai would have been aware of the Jimon moxibustion ritual is also suggested by their shared diagnostic focus: both Yōsai and the Jimon monks addressed their healing programs at disease-causing demons in the age of the “Final Dharma” (mappō 末法).11 Therefore, Yōsai’s promotion of mulberry (and tea) resonated closely with the broader trend toward pharmaceutical simplification in esoteric ritual practice, even as Yōsai ultimately argued for substances he felt were safer and more salubrious for the pathological problems at hand.

3. Problematics and Prescriptions: Yōsai’s Mulberry Remedies

Yōsai’s promotion of mulberry must be grasped within the larger structure of the Kissa yōjōki. The first fascicle of the work concerns restoring harmony to the five viscera by drinking tea, thus its title, “The Gate of Harmonizing the Five Viscera” (gozō wagō mon 五臓和合門). The second fascicle on mulberry concerns the expulsion of demonic entities and the treatment of demonic disease, hence, “The Gate of Exorcising Demons” (kenjo kimi mon 遣除鬼魅門). This binary structure corresponds neatly to the distinction medical historians sometimes draw between “functional” and “ontological” medicine: functional medicine pertains to a restoration of balance between viscera and/or with other constituent elements of the body, whereas ontological medicine, looking outward, is concerned with protecting against or ridding the body of exogenous pathological agents (Hinrichs 2015).

In the first fascicle, Yōsai establishes the problem of visceral imbalance by highlighting a pervasive lack in the Japanese diet of bitter flavored foods. In the second fascicle, he shifts focus beyond the body by evoking the chronotope of the age of the “Final Dharma” to establish the contemporary problem of rampant demonic disease in Japan. According to this idea, two millennia have already passed since the Buddha Śākyamuni entered nirvana, throwing the world into a state of degeneration and decline. Thought in Japan to have begun in 1052, the age of the Final Dharma was seen among many in the Heian period as having serious social and soteriological implications. Yōsai described the situation in this way: “In the age of the Final Dharma, when the lifespan of a person amounts to one-hundred years, the four monastic communities will in great numbers violate proper deportment. When people do not accord with the teachings of the Buddha, the realm will be thrown into wild chaos and the hundred generations will pass away. In these times there will be demons and spirits that will send the realm into chaos and antagonize the people…” (Mori 1999, p. 355).

Yōsai’s focus in the Kissa yōjōki is above all with the medical and pathological consequences of the age of the Final Dharma. As he notes in the preface, the world has long been without Jīvaka (Giba 耆婆), the famous healer who attended directly to the Buddha, and Shennong 神農, the legendary patriarch of Chinese materia medica (Mori 1999, p. 345). Without these illustrious exemplars of medicine, physicians struggle to coordinate pulse diagnosis with the treatments they administer, and patients suffer from this misguided practice with their lives. Worse still, as Yōsai explains in the second fascicle, the effulgence of the Buddha’s reign in the world having long faded, the darkness of the present moment is characterized by a proliferation of malignant beings in the way of demons and spirits (kimi 鬼魅) (Mori 1999, p. 355). He then describes five major afflictions that had become common in Japan as a result of the extended absence of the Buddha: drinking water disease (insuibyō 飲水病); wind struck (chūfū 中風)—hands and feet do not obey the mind disease; not eating disease (fushokubyō 不食病); sore disease (sōbyō 瘡病); and lower-leg pneuma disease (kakkebyō 脚気).12 These chief ailments of the day, Yōsai contends, owe to the pathological pandemonium of the Final Dharma.

The problematic thus established, Yōsai goes on to prescribe mulberry against diseases caused by demons. Yōsai offers as many as nine ways mulberry can be used therapeutically: mulberry-wood congee, mulberry-wood decoction, mulberry-wood cordial, mulberry roots (for chewing on), mulberry-wood pillow (for sleeping on), mulberry leaf tea, pellets made from honey and dried mulberries, and mulberry wood to be used as a staff or rosary. Unlike tea then—only the leaves of which are to be consumed as a beverage—Yōsai’s prescriptions exploit nearly every usable part of the mulberry tree, with a notable emphasis on consuming the wood itself. A few of these uses can be recognized as classically medical, some hygienic, and others related to nutrition. Still others, such as the use of objects made of mulberry, are more thaumaturgical in the sense they are presumed to work without direct consumption of the material. However, when Yōsai goes on to articulate his argument for mulberry’s efficacy, he does so primarily in spatial terms. In particular, he claims repeatedly that if one uses mulberry in these ways, demonic entities will be unable to come near. The utility of this apotropaic and repellant property of mulberry would be self-evident to anybody who felt they were living in a realm stalked by pathogenic demons, as many in the early thirteenth century did.

What sources did Yōsai draw upon in making this spatial claim about mulberry’s apotropaic efficacy? Scholars have been quick to note Yōsai’s exhaustive use of classical Chinese encyclopedic and materia medica (honzō 本草; Ch. bencao) texts. Mori (1999, p. 476) has demonstrated that the first fascicle on tea draws extensively from the Taiping yulan 太平御覧, whereas the second fascicle leans heavily on the late-eleventh century Zhenglei bencao 證類本草. In fact, the second fascicle is much less derivative than the first, containing far fewer direct borrowings from the main source text. Moreover, although many of the seventeen hundred total substances in the Zhenglei bencao are noted to be effective against demonic diseases, such demonifugic effects are not noted in the work’s descriptions of mulberry from which Yōsai drew (pp. 358–59). Thus, although it is indisputable that Yōsai based some technical aspects of his mulberry prescriptions on the Zhenglei bencao, the inspiration for his promotion of mulberry as an apotropaic agent against demonic disease lies elsewhere.

Given that Yōsai took two trips to Song China, one in 1168 and the second in 1187, contemporary medical practice on the ground in China may have inspired his thinking. Indeed, in the Kissa yōjōki he occasionally claims that his knowledge is based on these experiences. However, his mention of such experiences abroad can also be read as part of a rhetorical strategy to bolster his authority on these subjects for his less-traveled audience in Japan. Regardless, we lack relevant records from China in this period to verify his claims. On the other hand, there is some indication that mulberry was consumed in decoctions in Japan before and during Yōsai’s lifetime. For example, a hijiri known as Shinjaku-bō 心寂房 (d. 1231) is recorded preparing a decoction with mulberry, chrysanthemum, and Chinese plantain (Drott 2010, pp. 252–53). According to a later record in the Keiran shūyōshū, Tani lineage 谷流 founder Kōgei 皇慶 (977–1049), when suffering from a serious illness, dreamed of a visit from the god Indra (Taishakuten 帝釈天), who instructed him to drink a mulberry decoction made from alcohol daily, even if this meant breaking his precepts (T. 2410, 76: pp. 783c20–784a6). This account is significant because Yōsai is known to have respected the teachings of Kōgei and because Kōshū, the author of the Keiran shūyōshū, saw himself as a recipient of Yōsai’s transmissions (Mano 2014, p. 83). Other entries in courtier diaries from closer to Yōsai’s time curiously suggest mulberry was sometimes tried in place of mugwort as the tinder for moxibustion. Kujō Kanezane 九条兼実 (1149–1207), a frequent self-experimenter of moxibustion, once used mulberry for this purpose. Because members of his household were not as familiar with the smell of burning mulberry as they were of the mugwort typically used for moxibustion, they panicked, thinking there must be a fire in the mansion (Gyokuyō, vol. 7, p. 206). Another example of mulberry being burned as moxibustion is mentioned by Fujiwara no Teika 藤原定家 (1162–1241) in his Meigetsuki 明月記 (vol. 1, p. 163). As intriguing as these examples are for assessing the medicinal use of mulberry in this period, they give no indication that mulberry was seen as efficacious against demonic disease, the centerpiece of Yōsai’s claim.

Let us turn, then, to consider the passages in which Yōsai makes his case for the efficacy of mulberry in the Kissa yōjōki:

The five illnesses described above are all caused by demons and spirits during the age of the Final Dharma. The reason why mulberry is used to treat all of them is because mulberry is the miraculous tree under which the buddhas of the past realized the Way. When this tree is used as milkwood in the fire ceremony, all demons and spirits scatter and flee. Also, this is an appropriate wood for rites of averting calamities.

(Mori 1999, pp. 357–58)

Yōsai’s argument in this passage contains two major claims. The first is that mulberry is identical to the bodhi tree (bodaiju 菩提樹) under which past buddhas attained awakening. The second is that mulberry is “milkwood”, a type of wood burned in the esoteric fire ceremony that was understood to have demonifugic properties. As Yōsai suggests in an ancillary claim, this wood (and mulberry in particular) was used for rituals meant to avert disasters.

The two claims here seem at first unrelated. One gestures toward a moment that defines the origins of the Buddhist tradition as a historical tradition, namely the awakening of Śākyamuni under the bodhi tree. The latter claim, in contrast, seems to be no more than a minor practical detail of esoteric ritual practice. Moreover, it is only the second claim about milkwood that appears related to Yōsai’s assertion about mulberry’s power to prevent demons from approaching, because he notes that demons “scatter and flee” when the wood is burned. In fact, however, these apparently disparate claims were related in Yōsai’s thought. In the following sections, I reconstruct Yōsai’s logic in connecting mulberry to the bodhi tree, milkwood, and expelling demons. We shall see that not only are these three ideas tied to one another but also that unpacking their relationship helps us to grasp the significance of mulberry in both the Kissa yōjōki and in the context of Yōsai’s career.

4. Milkwood and Milk in Esoteric Buddhist Rites

We begin with Yōsai’s identification of mulberry as “milkwood”. As a Taimitsu monk, Yōsai would have been well versed in the goma fire ceremony, the foundational practice for nearly all rites in esoteric Buddhism. As noted above, the ceremony is performed in front of an altar centering around a hearth into which the presiding priest will toss an assortment of medicines, aromatics, and oils into the flames as offerings to the deity. Various types of wood are prescribed as the fuel for the fire; milkwood constitutes one category of goma wood. Varieties of milkwood that appear with some frequency in esoteric texts known or written in Japan include gōkan 合歡 (or nemunoki; Skt. siria, acacia sirisa); nigaki 苦練木 (Picrasma quassioides Benn), literally “bitter tree”; kazunoki 穀木 (also known as nurude 白膠木), literally “grain tree”; and mulberry. The wood prescribed depends on the objective of the rite, a relationship often spelled out in liturgical literature. For example, trees with a sweet taste were often prescribed for averting calamities (sokusai 息災), flowering trees for rites to attract one’s object of desire (keiai 敬愛), fruiting trees for increasing benefits (zōyaku 増益), bitter trees for the subjugation of demons and enemies (chōbuku 調伏; Skt. ābhicaraka), and trees with thorns for rites to capture deities to do one’s bidding (kōshō 鉤召) (Maku 1974, pp. 17–18; see also Maku 2013, pp. 127–51). Thus, in esoteric ritual discourse, specific types of woods are linked to specific ritual objectives by way of a symbolic logic that reflects the distinctive materiality of the tree to be used: sweetness mollifies, flowers allure, fruiting represents generation, bitterness repels and subdues, and thorns ensnare. As a student of this ritual literature, Yōsai was no stranger to this esoteric mode of symbolic and associative thinking.

Etymologically speaking, milkwood specifically refers to a type of unseasoned wood that, when burned in the fire ceremony, exudes a milky white sap, or latex. Mulberry exudes such a sap and is therefore often included in the category.13 In fact, the sap of mulberry was sometimes separately prescribed in ritual documents not simply as milkwood but as a substitute for milk itself. For example, in one text calling for “milk liquid” (nyūjū 乳汁), mulberry and kazunoki are given as viable options (Jingangding dayuqie bimi xindi famen yijue, T., 39: pp. 811b14–811b15). In the Gyōrin shō 行林抄, we read that if a baby has a swelling on the tongue and cannot receive milk from their mother, the adept is to extract juice from a mulberry tree in the east and smear this on the baby’s tongue while chanting a spell.14 In the Keiran shūyōshū, Kōshū explicitly notes that if cow’s milk is not available for use in the ritual then mulberry may be used as a substitute. Incidentally, Kōshū attributes this and other details about milk to an “oral transmission” (kuden 口伝) of Yōjō Sōjō 葉上僧正, a reference to Yōsai. Moreover, this transmission appears in a longer passage pertaining to the gumonjihō 求聞持法, a rite Yōsai is known to have mastered at age eighteen (Taga 1965, pp. 18–19).

Milk was an important ritual and medicinal substance in Buddhist rites across East Asia (Kotyk 2021). As a consequence, milk substitutes would have played a key role in the transmission and performance of such rites. As I note later, one reason why mulberry and other latex-producing milkwood would have been used to substitute milk in ritual was because milk was likely not widely available in Japan in the late Heian and early Kamakura periods. What the examples above suggest is that those who made these substitutions were motivated less by a concern for nutritional felicity and more by a correlative and symbolic logic that prioritizes morphology—in esoteric terms, sōbō 相貌, the manifest appearance, form, or shape. According to this logic, mulberry-milk’s material resemblance with cow and human milk makes it sufficiently equivalent to those substances for practical and symbolic purposes. Although we do not find in the Kissa yōjōki a direct statement about mulberry as a substitute for milk, that Kōshū would later understand this to be one of Yōsai’s teachings is significant. It suggests that in Yōsai’s thinking, mulberry was linked not only to milkwood but also, by extension, to milk. Indeed, we will see shortly that milk is a substance whose symbolic potency is embedded within aspects of his arguments in the Kissa yōjōki.

5. Mulberry as the Bodhi Tree in Medieval Chinese Texts

Yosai also identifies mulberry as a bodhi tree, the tree under which past buddhas attained awakening. This is, at first glance, a curious statement. Śākyamuni’s bodhi tree, referred to in Sanskrit as aśvattha (Ch. ashuotashu 阿説他樹), is known to be a fig tree, specifically Ficus religiosa, the sacred fig. Moreover, mulberry is not counted among any of the bodhi trees associated with the other six buddhas of the past.15 Yet in a wide variety of texts from medieval China, especially esoteric liturgical literature, mulberry was frequently given as an appropriate substitute for the bodhi tree. For example, a passage in the Scripture of the Great Peacock Spell King (Dakongque zhouwang jing 大孔雀呪王経), translated by Yijing 義淨 (653–713), describes a rite in which offerings are to be placed on an altar on top of leaves from a bodhi tree. A note specifies that if the adept does not have bodhi tree leaves available, they should instead use leaves from the mulberry tree, which are to be placed in front of the buddha icon (T. 985, 19: p. 476c24).

This example suggests that, just as we noted with mulberry sap and milk, morphological similarity constituted for some Buddhist practitioners sufficient reason to use mulberry as a substitute for the bodhi tree. The leaves of the white mulberry, when configured in a heart-shaped form, closely resemble the leaves of the bodhi tree, with the exception of the latter’s elongated drip tip. This resemblance has occasionally made it difficult to differentiate the leaves of these two trees. For example, Iwama Machiko (Iwama 2015, pp. 151–53) describes a type of tianmu (Jp. tenmoku 天目) tea bowl produced during the twelfth century in Song China in the Jizhou kilns of the Jiangxi region, distinctive for the leaf skeleton that is sintered into the black lacquer. Scholars have long struggled to identify the leaf, but the two most likely candidates have always been mulberry and the sacred fig. Guo Xuelei has recently advanced a more conclusive theory that the imprinted leaf is mulberry, given that, one, the Jiangxi region was a flourishing site for sericulture, and two, the bodhi tree would not have been readily available, its distribution in China being limited to tropical regions such as Guangdong and Yunnan. Comparisons between mulberry leaves and those of the bodhi tree were made in Japan as well. In his Honzō ikkegen 本草一家言, Matsuoka Joan 松岡恕庵 (1669–1747) would note the similarity between the leaves of these two trees as a way to identify “mountain mulberry”, a common type of mulberry in Japan (vol. 2, fasc. 4).

A more significant reason that practitioners substituted the bodhi tree with mulberry in esoteric ritual practice relates to the fact that the wood from both trees was used in esoteric rituals as a form of milkwood. Like mulberry, the sacred fig exudes a milky white sap. Today, botanists know that the mulberry and the sacred fig are genetically related to one another, as both belong to the Moraceae family, that is, the Mulberry family, almost all varieties of which exude a kind of latex (Konno et al. 2006). It goes without saying that Buddhists in medieval China and Japan were unaware of the genetic link, but this information was not needed. Rather, it was the exudation of white sap that these woods share, plain to the eye of any observer, which qualified both as a kind of literal milkwood tree. It was this similarity that Buddhists often gave explicitly as justification for their interchangeability in ritual performance.

For example, in the Scripture Outlining Recitations and Contemplations of the Yoga of the Peak of the Vajra (Jingangding yujia zhong lüechu niansong jing金剛頂瑜伽中略出念誦經), attributed to Vajrabodhi (671–741), we read: “Take the Auspicious Tree [i.e., the bodhi tree] as firewood. If this tree is not available, use a tree with white sap to substitute for it, such as the grain [tree, i.e., kazunoki], mulberry, or [others like this]” (T. 866, 18: pp. 252c16–252c17). In the Commentary to the Mahāvairocana Sūtra (Da Piluzhena chengfo jing shu 大毘盧遮那成佛經疏), translated by Yixing 一行 (683–727), we read: “These two trees are the bodhi trees for the buddhas of the past. If you do not have them, you should seek out a milk tree, that is, [trees such as] the mulberry or grain [tree]” (T. 1796, 39: pp. 626c21–626c22). In the longer passage these “two trees” are given as aśvattha, the bodhi tree of Śākyamuni, and uḍumbara (Ch. youtanboluo 優曇鉢羅), the bodhi tree of Kanakamuni 拘那含牟尼, the fifth of the seven buddhas of the past (Shimizu 2010, p. 20). The uḍumbara is also known in the Buddhist botanical imagination as a tree that blooms only once in three thousand (or one thousand) years, and thus symbolizes the extraordinarily rare occurrence of a buddha appearing in the world. Like the aśvattha, scholars also identify the uḍumbara as a fig, namely Ficus glomerata (Shimizu 2010, p. 25). This is true of the nyagrodha tree as well, the bodhi tree for Kāśyapa 迦葉佛, the sixth of the seven buddhas of the past, which is identified as Ficus bengalensis (Shimizu 2010, p. 27). At any rate, the logic in the Commentary to the Mahāvairocana Sūtra passage is the same as that found in the Scripture Outlining Recitations and Contemplations of the Yoga of the Peak of the Vajra: a bodhi tree can be substituted with mulberry or kazunoki because they are “milk trees”, which is to say they produce white sap.

All the ritual texts examined thus far authorizing mulberry as a substitute for the bodhi tree were seen as authoritative esoteric scriptures in Japan. The Scripture of the Great Peacock Spell King was one important source text for the ritual addressed to the Peacock Wisdom King (Kujaku Myōō 孔雀明王), which was performed by Tendai monks to treat illness (see e.g., Tachi 2010, p. 573). Although introduced to Japan initially by Kūkai, the Scripture Outlining Recitations and Contemplations of the Yoga of the Peak of the Vajra was later imported by Ennin 円仁 (794–864), a pivotal figure for the early development of Tendai esotericism; his copy would have been frequently consulted by later generations of Tendai students (Tomabechi 2022). Yixing’s Commentary to the Mahāvairocana Sūtra was likewise a foundational text read widely by Tendai monks (see e.g., Groner 2021). Given the established place of these esoteric scriptures in Tendai study and practice, we can conclude that Yōsai would have carefully surveyed them as well. In this way, Yōsai would easily come to learn of the functional and symbolic ties between mulberry and the bodhi tree.

The richest description of a “substitution” of the bodhi tree with mulberry in medieval China actually comes not from an esoteric ritual text but rather from the Qianjin yifang 千金翼方, an important work of classical medicine by Sun Simiao 孫思邈 (581–682). Sun was often celebrated as the “king of physicians” and was certainly one of the greatest authors of medical compilations in the Tang period (618–907). These compilations, moreover, reflect in certain passages a deep understanding of Buddhist ideas (Sivin 2017). This much is evident in the section on mulberry that appears in Qianjin yifang under the heading, “Formula for Correct Meditation” (zheng chan fang 正禪方):

Spring mulberry ear, seeds from summer mulberry, leaves from autumn mulberry.16 Take these three flavors, pound [them into powder], and sift them evenly. Take one dou of water and boil one sheng of adzuki beans, making it very hot. [Then] boil one sheng of the mulberry powder to a slight boil and add it to fermented bean paste to consume it, filling one’s stomach with it three times per day without fail. After three days, toss out some of the beans. Your body will be light, your eyes clear, with no need for sleep. In ten days, you will awaken to a far-reaching wisdom and enter the first level of dhyāna. If you consume it for twenty days, you will reach the second dhyāna. After one hundred days, you will obtain the third dhyāna. And after one year, you will obtain the fourth dhyāna, [enabling you to] see the ten-thousand characteristics [of the external world], as if the annihilation of the desire realm and the contemplation of phenomena were [all] in the very palm of your hand to observe, and you will see your buddha nature.

(juan 12, p. 147)

Although there is no evidence from the Kissa yōjōki that Yōsai was aware of Sun’s prescription, it is worth noting the extent to which it differs from but also anticipates Yōsai’s own strategy of linking the bodhi tree and mulberry. Unlike Yōsai, Sun does not explicitly state that mulberry is a bodhi tree, yet this is arguably the implication of his description of how the benefits of consuming mulberry porridge mirror the contemplative attainments gained by Śākyamuni Buddha when he famously meditated under the bodhi tree. Sun goes so far as to reproduce Śākyamuni’s specific progression through four stages of meditative absorption (Ch. chanding 禅定; Skt. dhyāna), promising readers that a similar refinement of contemplative capacity may be experienced by those who continue to consume the mulberry porridge without fail. In so doing, Sun would appear to be aware that some Buddhists in his day had closely linked these two trees or even understood them to share a deeper identity. However, whereas Sun ultimately stresses the contemplative and soteriological benefits of consuming mulberry, Yōsai claims that those who consume or use mulberry will be free of disease by virtue of keeping demons at bay.

6. Milk Congee and the Bodhi Tree in the Biography of the Buddha

The preceding sections noted links between mulberry, bodhi trees, and milkwood in esoteric liturgical discourses and one medical text linking mulberry with the bodhi tree in relation to the story of Śākyamuni’s awakening. Some of the connections we have seen point to milk as another substance some authors may have had in mind as well, given that the white latex of mulberry and the bodhi tree both conceivably functioned as milk analogues. Yet there remain certain aspects of Yōsai’s argument for the efficacy of mulberry that these precedents do not fully explain. For example, besides the mulberry recipes in the Zhenglei bencao upon which Yōsai relied, what linked these substances with the restoration of health, for which purpose Yōsai wrote his Kissa yōjōki? Moreover, from whence does Yōsai derive the more specific notion that mulberry would make those who consume or use it impervious to the approach of disease-causing demons, a claim which constitutes a core component of his promotion of mulberry as a therapeutic agent?

One viable approach to exploring these remaining questions is to turn away from esoteric liturgical literature and, following the hint offered by Sun’s “Formula for Correct Meditation”, directly examine the biography of Śākyamuni Buddha.17 It is, after all, the biography of Śākyamuni that constitutes the locus classicus for the significance of the bodhi tree in the Buddhist tradition. The biography of Śākyamuni was valued by Buddhists across sectarian affiliations in Yōsai’s time, with different versions of it being produced and included in anthologies such as the Konjaku monogatari shū 今昔物語集 (vol. 33, Tenjiku-bu 天竺部). For monks of the Tendai school, the biography of Śākyamuni would have been classified as an “exoteric teaching”, because in its most basic form it assumes the identity of Śākyamuni as an historical figure who attained awakening through a gradual process that saw final fruition under the bodhi tree at a specific moment in time.18 Indeed, one important genre of Buddha biographies (butsuden 仏伝) in medieval Japan was the Shaka hassō 釈迦八相. As the title suggests, the Shaka hassō narrative is structured according to “eight stages [in the life of] Śākyamuni”, half of which pertain to his time prior to awakening as the prince Siddhārtha (Shitta Taishi 悉達太子). Those eight stages are as follows: (1) Above Heaven and Below Heaven (jōten geten 上天下天): the Buddha’s past life with Kāśyapa Buddha and his time residing in and eventual descent from Tuṣita Heaven; (2) Conception (takutai 託胎): conception in the womb of his mother, Queen Māyā; (3) Leaving the Womb (shuttai 出胎): his birth; (4) Leaving the Household (shukke 出家); (5) Conquering King Māra (gōma 降魔); (6) Attaining the Way (jōdō 成道); (7) Turning the Dharma-Wheel (tenpōrin 転法輪); and (8) Nirvana (nehan 涅槃), his final passing.19

The importance of the biography of Śākyamuni to Yōsai is evident in the fact that he wrote his own version of the Shaka hassō in 1191, only a few years after returning from his second trip to China.20 Yōsai’s recognition that the biography is a patently exoteric teaching appears in the “Turning the Dharma-Wheel” section, in which he makes the following remark on how this part of the narrative is to be understood with respect to the broader corpus of exoteric teachings:

When people of later generations write into the stage of “Turning the Dharma Wheel” (the idea that Śākyamuni preached) the Flower Ornament (Kegon 華厳) [sutra], the well-balanced (Mahāyāna sutras), the Prajñā[paramita] (hannya 般若) [sutras], and the Lotus Sutra, they are writing without comprehending (the truth of the matter). The eight stages that led to (Śākyamuni’s) attainment of the Way constitute the surface of Hīnayāna (teachings), thus the Mahāyāna (teachings) ought not to be included in the stage of “Turning the Dharma-Wheel” (in the narrative). The facts (supporting this view) are abundant.

(Shaka hassō, p. 477)

Despite Yōsai’s identification of the “eight stages” of Śākyamuni’s biography as reflecting a Hīnayāna perspective, which we might reasonably take as implying that the narrative is not as profound as the Mahāyāna sutras classed in the same category of exoteric doctrines, nor the esoteric teachings, it is clear from the existence of Yōsai’s edition of the Shaka hassō that he took great interest in the biography. Most important for our purposes, the narrative in this text can be shown to have influenced Yōsai’s claims about the potency of mulberry. In the analysis that follows, I shall discuss the Nishi Honganji 西本願寺 edition, a version of the Shaka hassō attributed to Yōsai for which at least four other variant copies exist.21 I will also reference the Shaka nyorai hassō shidai 釈迦如来八相次第, a different medieval version dating to the fourteenth century.

The relevant section for our purposes is contained within a single stage in the narrative, “Conquering Māra” (Shaka hassō, pp. 470–72). We already have in this section title a suggestion of relevance to Yōsai’s argument, because the characters for “Conquering Māra” (gōma) can refer to the “subjugation” (gōbuku 降伏) of māras or demons. This is precisely the function to which milkwood was imagined to contribute in esoteric rites of subjugation, and it is also the function that Yōsai ascribes to mulberry in the Kissa yōjōki. As we will see, however, there are several additional elements of this narrative that offer insight into Yōsai’s thinking about mulberry and the associative and symbolic network in which it could be embedded.

The beginning of the “Conquering Māra” section finds the prince Siddhārtha at the bank of the Nairañjanā River utterly emaciated (“nothing but bones, skin, and sinew strung together”), the result of six years of grueling ascetic practices. Even as he teeters on the verge of death, the prince knows that the moment of “attaining the Way” is near. He also realizes that should he enter the “adamantine samādhi” (kongō yujō 金剛兪定) leading to awakening in his present cadaverous state, he would risk substantiating the “doctrines of heretical ways” (gedō no gi 外道ノ義), which is to say, the program of ascetic practice that led him to this point. Hence, the prince decides he will first “fill out his skin” (hifu enman shite 皮膚 円満シテ) by consuming some “milk congee” (nyū no kayu 乳ノカユ), whereupon the Deva Pure Abode (Jōgotenshi 淨居天子) instructs an ox-herder’s daughter named Nandā Balajā (Nanda Bara 難陀波羅) to make the congee, which she does in miraculous fashion:

She milked one thousand cows and fed their milk to five hundred cows; then she milked those five hundred cows and fed their milk to two hundred cows, continuing in this way until she had fed the milk to just two cows, which she then milked and from which made the milk congee. She poured the congee into a golden bowl. After (the prince) consumed the milk, he tossed the golden bowl into the Nairañjanā River.

(Shaka hassō, p. 471)

Having regained his strength by drinking the milk congee, the prince sits down on top of a pile of grass given to him by the god Indra under the bodhi tree. At that moment, the distant palace of King Māra grew dark. Fearing the prince will succeed at his task, Māra dispatches his daughters to seduce him, but the prince immediately turns the women into old hags with horrific appearances. Māra then summons a battalion of demons eight billion strong, yet even then we are told, “not a single hair on the prince swayed”. The army launches all manner of halberd, sword, and stone tile toward the meditator, only to witness these weapons transform in mid-air into lotus flowers and jewels. The soldiers find themselves under the control of the prince’s samādhi, and Māra is forced to admit his defeat.

In a summary at the end of this section in the Shaka hassō, Yōsai revisits a few of the major takeaways and adds a couple new points. The summary reemphasizes the importance of milk congee for enabling the prince to realize the Way, reiterating that his accomplishment was not the result of his earlier ascetic endeavors. Moreover, we learn here that consuming the congee enabled the prince to manifest the “thirty-two major and eighty minor marks”, the physical characteristics with which awakened beings are endowed. The passage adds that after consuming the congee, the prince first went to Prāgbodhi Mountain in order to realize the Way. Because the mountain ceaselessly shook beneath him, however, he moved to the site of the bodhi tree, with the help of directions given to him by Deva Pure Abode.

Mulberry does not figure in any way in this narrative, nor in any other biography of the Buddha of which I am aware. Yet we can nevertheless imagine—as we have observed medieval Chinese and Japanese monks were inclined to do—how mulberry might serve as a surrogate for both the milk and the bodhi tree that play such important roles in this story. More specifically, if we take what the narrative conveys about milk and the bodhi tree and consider it alongside Yōsai’s argument for the efficacy of mulberry, we begin to better understand what he had in mind when he formulated that argument.

We must first consider milk, which functions as a nourishing and restorative medicine for the prince. In the narrative as written in Japanese, “milk congee” minimally refers to a combination of milk and rice, because kayu denotes a kind of rice congee in East Asia. That said, it is arguably the therapeutic potency of the milk that is emphasized. The importance of the milk in particular is conveyed in the narrative’s description of the fantastical process by which the ox-herder’s daughter produces the milk, a miraculous procedure in which the milk of a thousand cows is condensed down multiple times until a super-critical extract of sorts is procured. The significance of this aspect of the narrative is also confirmed by the fact that similar descriptions of this miraculous process can be found in other biographies of the Buddha composed elsewhere in the Buddhist world, including the Lalitavistara, and the Sinhala Thūpavaṃsa, which was composed in Sri Lanka not long after Yōsai compiled his Kissa yōjōki.22

The narrative showcasing of the therapeutic power of milk is intriguing when we consider that milk and other dairy products may not have been readily available to Yōsai. Although it is evident that such products existed earlier in the Heian period, the question of their existence in the late Heian and early Kamakura periods is less clear. One dairy product known as raku 酪, which some scholars understand as a kind of yogurt or condensed milk, had a porridge-like consistency and was thus glossed with the vernacular term “milk congee” (nyū no kayu 迩宇能可遊) in the Wamyō ruijū shō 和名類聚抄 (922–931) (fasc. 16) (Satō 2012, p. 49). Given the use of this vernacular term, some scholars contend that this product must have existed in ancient Japan. The same gloss in kana appears for nyūraku in the Iroha jiruishō 色葉字類抄, suggesting the term had not lost its significance in the late twelfth century (upper fasc., under ni 仁). The Shaka hassō (1191) uses the same term, as we have seen, but with the distinct meaning of “milk congee”. That the term had multiple referents in the late Heian period suggests some familiarity with milk products. Moreover, several prescriptions involving milk products can be found in the Kakuzenshō 覚禅抄 by the Shingon monk Kakuzen 覚禅 (1143–ca. 1213), who was only a couple years younger than Yōsai. Such Buddhist liturgical texts, as well as other documentary sources from the Heian period, demonstrate that milk products were likely used for both medical and ritual purposes and were often prepared in the form of a porridge. In one prescription in the Kakuzenshō, for example, mention is made of mi, or nyūmi 乳糜 (alt. nyūbi), a milk porridge of thinner consistency (Satō 2012, p. 50). This term appears as an alternative name for the milk congee in the version of the Buddha’s biography found in the Shaka nyorai hassō shidai.

On the other hand, numerous scholars cast doubt on the existence of milk products after the Heian period (Ehara et al. 2009; Satō 2012; Ishige 2015; Kotyk 2021). Indeed, it is indisputable that the documentary record for milk and dairy products attenuates in the early Kamakura period. Even existing records do not always constitute unequivocal evidence. Because liturgical texts such as the Kakuzenshō draw from continental sources, frequent mention is made of substances that may in fact have been difficult to obtain at that time. A cautious conclusion would be that even if milk products were available to Yōsai, it was probably not the case that they were available often or in large quantities to him or other Buddhists.

The absence of milk in Japan makes the imagination of milk congee in the Buddha’s biography significant when we return to the role of mulberry as a milk substitute. As we have seen, mulberry was a conceivable surrogate for milk that, unlike milk, would have been widely available.23 For Yōsai, it would seem that mulberry functioned as an exceptional substitute precisely because it could be used to make a congee, perhaps one that could serve at least symbolically comparable to the congee that restored the health of the prince. Although Yōsai mentions numerous mulberry recipes and uses, it is not insignificant that mulberry congee is mentioned more often in the Kissa yōjōki than any other form. Indeed, he makes a point to prescribe this congee in each of the individual sections for the five current diseases he discusses. Moreover, the section on making the mulberry congee is the first to appear among the list of the uses of mulberry, and it is also the longest. In that section, Yōsai carefully provides the reader with detailed instructions for making and consuming the congee correctly so that it is efficacious and instructs the reader to drink it every morning. If we accept that Yōsai was likely impressed by the decisive role of milk congee in the biography of the Buddha, his emphasis on mulberry congee in the Kissa yōjōki begins to make more sense.

Besides the role milk congee plays as a restorative for the prince, another noteworthy aspect of the milk congee in the Shaka hassō is how it marks the Buddhist distinction between heterodox and orthodox paths to awakening, the former focused on spiritual advancement through body-denying austerities and the latter on advancement built on a concern and care for the physical body. Recalling the narrative, it was precisely when the prince consumed the milk congee that he pivoted away from the heterodox program and toward the orthodox path. Although the distinction is taken to be basic to Buddhist practice (as expressed in the concept of the “Middle Way”), explicit mentions of it in medieval Japanese texts are not necessarily common. Therefore, it is significant to find the distinction made explicitly in the Onjōji denki 園城寺伝記 (1333–1392, 10 vols.; DNBZ 127) in a section on “nourishing life” (yōjō 養生). The Onjōji denki is a fourteenth-century collection of records concerning Onjōji, a temple with whom Yōsai had several ties through his father and disciples.24 The passage in question from this work almost definitely draws from Yōsai’s prescription of mulberry congee in the Kissa yōjōki, making it one of the only medieval sources to do so. The passage opens as follows:

In general, there are two types of practitioners on the Buddha Way. The first, unconcerned with the life of the body, performs difficult practices and ascetic practices. The second type nourishes their life, assists their body, and [in this way] facilitates practice of the Buddha Way. The secret method of nourishing life is, in the first, pine needles.

[…] (DNBZ 127, p. 92)

After providing recipes for pine needles, rice congee, and willow, the record describes a mulberry congee method for eliminating “epidemic affliction” (ekishitsu除疫). The instructions follow Yōsai’s own mulberry congee recipe nearly verbatim, with the exception of some abbreviations. What is interesting, then, is that the Onjōji denki prescribes mulberry congee for the same reason as that suggested in the biography of the Buddha: to nourish the body of the practitioner, and here too this is defined as distinguishing the path premised on bodily care from an ascetic path that disregards the body. It is also notable that the medicinal materials mentioned in this section of the Onjōji denki are all easily obtainable plants (pine needles, rice congee, willow, mulberry), suggesting a practical focus on local materials despite the recent availability of much newly imported materia medica, such as those discussed extensively by Kajiwara Shōzen 梶原性全 (1265–1337) (Goble 2011).25 We thus see here the influence of Yōsai as well as what might be an enduring preference in monastic medical practice toward a simplified pharmacopeia.26

The second aspect of the Shaka hassō germane for thinking about Yōsai’s promotion of mulberry pertains to the bodhi tree and the efficacy with which it is imbued in the “Conquering Māra” episode. On first read, it may appear that the power that drives the dynamic battle with King Māra featured in this scene is not exhibited by the tree but rather the prince who meditates beneath it. Yet if we consider power in spatial terms, and not simply causative ones, then we can begin to recover an imagination of the distinctive presence commanded by the bodhi tree. The narrative leaves no doubt that this is no ordinary tree. Recall that in the final summary in the Shaka hassō, we learn that the prince traveled to the bodhi tree after having first attempting to realize the Way on Prāgbodhi Mountain. The mountain shook, however, demonstrating that even a mountain would prove unfit for the prince’s momentous task. In contrast, the narrative suggests that the seat under the bodhi tree marks a stable bodhimanda (dōjō 道場), a site durable enough to withstand the earth-shaking convulsions that accompany the prince’s accomplishment (Shaka nyorai hassō shidai, p. 385). Additional details about the spatial agency of the bodhi tree are given in the Shaka nyorai hassō shidai. For example, we learn that before the prince goes to the bodhi tree, Māra has already realized that the tree marks the site where the buddhas of the past attained awakening, so he sends an elder yakṣa to stand guard. When the prince arrives, the yakṣa knows immediately that the prince too will become a buddha on this spot and flies up to inform Māra. In this way, the narrative marks the place of the bodhi tree as special owing to its long history as a site of awakenings. The power of the site is highlighted again when, shortly later in the narrative, Māra insists that the prince leave his seat, warning him that evil rākṣasa who snatch human vitality live under the bodhi tree. However, this the reader soon learns to be another of Māra’s ploys to dislodge the determined prince, because the narrative will soon demonstrate that the tree marks a boundary into which evil and demonic forces cannot invade.

The spatial power described in the Shaka hassō of most relevance for our purposes relates to how the bodhi tree stands as the central landmark of the conquering of Māra and his demons. In the narrative, Māra summons his army around the bodhi tree to thwart the prince, but the demon hoards find that the halberds and arrows they launch do not merely miss their target but are instead transformed into flowers. It is true that the narrative gives final ascription of this repulsion of Māra’s forces to the prince’s samādhi. However, from another perspective, the bodhi tree is critical in marking the territory into which Māra’s demons cannot encroach. Further, it is worth noting that the Buddhist tradition, in incorporating the bodhi tree into its mythology of Śākyamuni, was in fact drawing upon an earlier lore surrounding the aśvattha (Ficus religiosa) as a powerful, divine-like presence in its own right. In the Atharva veda, for example, it was already stated that the tree could “drive away enemies with its mystical powers” (Shimizu 2010, pp. 12–13). This attribution in turn relates to the violent nature of the Ficus religiosa as a parasitic epiphyte: when a seed of the tree falls into the crevice of another tree, aerial roots are sent down that will strangle and eventually displace the original tree (Shimizu 2010, p. 14; Shanahan 2016, pp. 31, 35). Hence, one early prayer for subduing enemies addressed the tree in this manner: “… As thou climbest up the trees, O aśvattha, and renderest them subordinate, thus do thou split in two the head of my enemy, and overcome him! …” (Shimizu 2010, fn. 37, p. 12). If the biography of the Buddha’s defeat of Māra drew on older mythology surrounding this commanding and even violent divine tree, it is easy to imagine how readers of that biography might come to re-ascribe the same tree with powers distinct from those of the meditating protagonist.

I would suggest that Yōsai was one such reader. He identified mulberry with the bodhi tree precisely because of the spatial efficacy this sacred tree exhibited in the conquering of demons and Māra. This identification allowed Yōsai to claim that, like the bodhi tree, mulberry possessed the power of establishing a demonifugic boundary around practitioners who consume or burn it. Thus, in the Kissa yōjōki Yōsai writes that when “mulberry branches are burned in the goma fire ceremony, demons scatter and flee”, and that “demons do not approach [the site] under the mulberry tree”. This latter statement echoes rather precisely what is said of the bodhi tree in the Buddha’s biography, yet here it is suggested that the desired repellant effect is to be expected even without the presence of the meditating prince. Yōsai also brings the biography’s language of spatial efficacy into descriptions of the efficacy for using objects made of mulberry: “If one holds on to this tree as a rosary, as a staff, or as a pillow, Māra (tenma 天魔) cannot invade, to say nothing of those lesser demons and spirits [who will have no chance] of approaching”. “Māra” in this statement reflects well the position of Yōsai’s argument between the biography of the Buddha and his present audience, for it can point either to the famous King Māra of the narrative or to a generalized category of demonic beings that obstruct practice, entities that we have noted were imagined to proliferate during the age of the Final Dharma, causing widespread disease. He concludes: “For this reason, I, Yōsai, know that there is no disease for which this tree will not demonstrate efficacy” (Kissa yōjōki, pp. 357–58).

7. The Bodhi Tree in the Biography of Yōsai

In introducing the Shaka hassō above, I noted that the work was written by Yōsai. This attribution is based in part on the preface to the Nishi Honganji edition, which includes the note, “(in) the words of Yōsai” (Yōsai no go 栄西語). Not all scholars have accepted this claim of authorship. In one of the first investigations of the work, Komine Kazuaki questioned the veracity of this attribution. One of Komine’s primary reasons for doing so was that the text appears to lack any explicit connection to Zen, which we might otherwise expect to see in all of the writings Yōsai authored after returning to Japan from his second trip to China. In a more recent evaluation, however, Sueki Fumihiko contends that it is more than plausible that Yōsai was the author.27 I agree with Sueki’s assessment. For one thing, at several points in this article we have observed the extent to which Yōsai drew upon esoteric discourse and practice. Although the narrative of “Kamakura New Buddhism” might prompt us to view Yōsai as having cast aside his previous esoteric leanings in order to establish Rinzai Zen as an exclusive new sect in Japan, numerous passages in the Kissa yōjōki make it clear that his esoteric training continued to inform his thinking. I would also suggest that the analysis on the Shaka hassō above provides additional supporting evidence for the notion that Yōsai authored this text. Yōsai’s argument for mulberry’s therapeutic efficacy in the Kissa yōjōki demonstrates he was deeply engaged with the biography of the Buddha in the latter years of his career; that he would have composed a biography himself is well within the bounds of possibility.

Indeed, Yōsai’s own life story cannot be understood without considering his engagement with the life of the Buddha. Yōsai’s biography in the Genkō shakusho 元亨釈書 (vol. 1, p. 29) reports that Yōsai had a strong desire to travel to India. In fact, a pilgrimage to India is thought to have been the main purpose of his second trip to China in 1187. Although he got further than most of his Japanese contemporaries, who never had the opportunity to leave the archipelago at all, the political situation on China’s frontiers meant that Yōsai’s ambitious pilgrimage was out of the question. After returning to Japan from this trip, Yōsai would lament missing his chance to bow before the eight stupas commemorating the celebrated sites of the Buddha’s life, the second of which is Bodhgayā in Magadha, the very sacred place where the Buddha defeated Māra and achieved enlightenment under the bodhi tree.

Yōsai’s unrealized aspirations might have spurred his decision to author a vernacular rendering of the Buddha’s biography, which he did soon after returning from his second trip to China (Eisai shū, p. 540). Recreating this narrative of the Buddha’s life in his own hand would surely not replace a literal pilgrimage to India but perhaps it served in substitution as a virtual pilgrimage of sorts. Yōsai had already made another remarkable attempt to do much the same, to bring some of the Buddha’s story and homeland back to Japan. When in China in 1189, Yōsai sent cuttings of the “bodhi tree” back to Japan on a merchant ship, the first of which were planted at Kashii Jingū 香椎神宮 (now within Hōonji 報恩寺) in Hakata 博多, Kyūshū, in 1190. This was not far from the future site of Shōfukuji 聖福寺, the temple he would establish there in 1195. A cutting was also cultivated at Tōdaiji in 1195; he would return in 1206 to succeed Chōgen 重源 (1121–1206) in steering the restoration of the temple following its destruction by Taira 平 forces during the Genpei war (1180–1185). Finally, one cutting was planted in the northeast quarter of Kenninji 建仁寺, which he built in 1202 (Genkō shakusho, vol. 1: pp. 33–34; Taga 1965, pp. 319–23).28 Just as we might see Yōsai as the “Johnny Appleseed” of tea in Japan, he also endeavored to plant the bodhi tree throughout the archipelago as well.

In this regard, Yōsai would have found himself in good company with countless other pious Buddhists in history. As the religion began spreading beyond India some centuries after the Buddha’s death, saplings of the bodhi tree were cast into a role similar to the Buddha’s relics, functioning for monastics and laypersons alike as a proxy for the Buddha’s “absent-presence” (Strong 2004, pp. 21, 151–57). As with the practice of installing relics in stupas, planting bodhi tree cuttings on fresh soil served to consecrate sacred sites for efficacious monastic practice and devotion. Notably, that devotion often came to be addressed toward the tree itself. For instance, in the Mahābodhivaṃsa, a Pāli history of the importation of the bodhi tree to Sinhala (Sri Lanka) by Saṅghamittā, the daughter of King Aśoka, many miracles are ascribed to a sapling taken from the original bodhi tree. It was said to emit light, to open hearts and bring joy, and even to plant itself, whereupon the earth shook (Shimizu 2010, p. 84). This magical sapling organically became the center around which Buddhists would establish the temple complexes of Anuradhapura, drawing to itself the worship of men, kings, queens, gods, and nāgas. Likewise, in his Kissa yōjōki, Yōsai calls mulberry a “spirit tree at which past buddhas attained the Way” (kako shobutsu jōdō no reiboku nari 過去諸仏成道之霊木也), thereby encoding mulberry with the history long ascribed to the divine bodhi tree.

However, there is one botanical twist in the story of Yōsai and his planting of the bodhi tree in Japan. The bodhi tree from which Yōsai made his cuttings was located at the famous Mt. Tiantai 天台山. This tree was itself famous, and of much value for Japanese pilgrims, because it was said to have originally been planted by Daosui 道邃, the teacher of Saichō 最澄 (766–822). (Saichō was the founder of the Tendai school in Japan who established Enryakuji 延暦寺, the temple where Yōsai trained.) Therefore, as it turns out, the bodhi tree from which Yōsai acquired cuttings on Mt. Tiantai was not, botanically speaking, the same type of tree as the famed bodhi tree of Śākyamuni; in other words, it was not the sacred fig. As noted previously, in China, the sacred fig can be found only at temples in the tropical and subtropical regions. Accordingly, elsewhere throughout China many different trees have been used as “bodhi tree” substitutes, most commonly ginkgo (Ch. yinxing 銀杏). The bodhi tree on Mt. Tiantai would have been a Chinese linden tree (Ch. nanjingduan 南京椴; Tilia miqueliana) (Wang et al. 2020). The reason, then, why the “bodhi trees” at Tōdaji and Kenninji today are in fact Chinese linden trees is because that was the kind of tree from which Yōsai received his cuttings in China. Still today, the word bodaiju (“bodhi tree”) in modern Japanese commonly refers to the Chinese linden and not the sacred fig.

Why then did Yōsai, the very person who brought this “bodhi tree” to the archipelago, not promote the linden against demonic disease in his Kissa yōjōki? We can only speculate, but it would appear that between the time of his second trip to China in 1187, when he acquired cuttings of the linden bodhi tree on Mt. Tiantai, and his writing of the Kissa yōjōki in 1211, Yōsai had an important realization. We have suggested here that he wanted to bring home the therapeutic power of Nandā’s milk congee offering, the substance that enabled the prince to nourish his body and thereby attain the Way through non-heretical means. He also wanted to bring home the apotropaic power of the bodhi tree, capable as it was of keeping Māra’s demonic armies at bay, a property that would be especially valuable during the age of the Final Dharma, the ruinous epoch of the Buddha’s absence. Perhaps then, given its established use in esoteric ritual as a form of milkwood, together with the fact that it produced a white latex just like the sacred fig, Yōsai had come to realize that mulberry was a more fitting substitute for the bodhi tree and one more directly suited to his therapeutic aims. Mulberry, much more so than the linden, enabled Yōsai to better “milk” the power of the bodhi tree and milk congee, neither of which were widely available on the archipelago in his time.

8. Conclusions

In the concluding section of his esoteric exegesis of the Lotus Sutra, the preeminent “exoteric” scripture of the Tendai school, Yōsai wrote, “Before the eyes of Jīvaka [i.e., the personal physician of Śākyamuni Buddha], all poisonous plants are transformed into medicinal plants” (Hokkekyō nyū shingonmon ketsu, p. 578). The gist of Yōsai’s analogy here, which he shared with many of his peers in the Tendai school, is that an esoteric reading of “exoteric” doctrines such as those presented in the Lotus Sutra promises a penetrating and integrative understanding that far surpasses any ordinary or superficial reading. Yet it is evident that for a monk as materially and botanically minded as Yōsai, the value of such an esoteric reading extended well beyond hermeneutics and scriptural exegesis. Turning from doctrinal texts to the physical world, an esoteric reading of material things promises to disclose an interconnected network of symbolic meanings and potentialities that might otherwise be hidden from view. Recalibrating one’s vision with “the eyes of Jīvaka”, even ordinary plants might appear with an amplified power, sacrality, and efficacy. If such an esoteric reading of the phenomenal world was compelling enough to spur medieval Tendai monks to conclude that even grasses and trees become buddhas (Stone 1999, pp. 27–31), it is not hard to imagine how this way of reading the world might have incited Yōsai to see the familiar mulberry as a divine bodhi tree.

In relating Yōsai’s comment on this esoteric vision to his specific arguments in the Kissa yōjōki, it is clear that a profound transformation of perspective was not required for mulberry to be seen as a powerful medicinal substance. Much of the groundwork for Yōsai’s argument for mulberry’s therapeutic and ritual efficacy was already in place when he picked up his brush to write the Kissa yōjōki. We have seen, for example, that materia medica literature from the continent spelled out certain therapeutic properties of mulberry that any reader with access to these works might exploit for their own healing program. We also saw how esoteric Buddhist liturgical texts identified mulberry as an important form of milkwood to be used in the fire ceremony. Those ritual texts also prescribed it as a viable “substitute”—or functional equivalent—for both milk and the bodhi tree. Although in this way key images of mulberry’s efficacy were already in place to some extent, it is equally clear that Yōsai, in bringing these images, symbols, and materials together for the first time, uncovered a network of potent associations that had never before been discerned so vividly.

Yōsai’s application of this esoteric vision to mulberry brings us again to the question of the relationship between “esoteric” and “exoteric” teachings in his thought. Traditional images of Yōsai in scholarship long focused on his promotion of Rinzai Zen in Japan as another example of “Kamakura New Buddhism”. Newer research, however, revealed the limitations of this image, demonstrating that he consistently engaged with esoteric doctrines over his long career. Indeed, as we have observed in this article, without an appreciation of Yōsai’s esoteric orientation, his promotion of mulberry would remain difficult to interpret and the second fascicle of the Kissa yōjōki would appear to have little significance.

On the other hand, however, we have also seen that numerous passages in the Kissa yōjōki point to an abiding influence one might overlook in leaning too heavily on his esoteric persona. This is especially true in terms of the ways he was influenced by the biography of the Buddha. It is true that in his esoteric exegesis of the Lotus Sutra Yōsai contends that “the bodhisattva [Śākyamuni] descended to Jambudvīpa, attained true awakening under the bodhi tree, subdued the ninety-five kinds of heresies, and turned the Dharma-Wheel at the instruction of Dainichi Nyorai”, and elsewhere that Śākyamuni and Dainichi are identical, of a “single body” (Hokkekyō nyū shingonmon ketsu, pp. 571, 573). Yet to establish theological hierarchy or equivalence in this way is not to dispense with the specificity of the story behind the identity. The captivating biography of Śākyamuni Buddha as an “historical” individual (which is to say, one who attains the Way through correct practice along successive stages) and all it describes—the momentous events, famous places, and potent materials—were of great interest to Yōsai, a fact confirmed by many aspects of his own career. In analyzing the Kissa yōjōki, it is in fact this “exoteric” biography of the Buddha that helps us to read the apparently disparate elements of his multifaceted argument for mulberry in a seamless and coherent way.

In the final analysis, however, the question of how to classify the individual pieces of this argument and his thought according to a binary of esoteric versus exoteric teachings risks projecting doctrinal and sectarian concerns that were not necessarily at the forefront of Yōsai’s mind when writing the Kissa yōjōki, for indeed this matter is not mentioned once in the text. It is perhaps more important to ask, as we have sought to do here, what kinds of ritual, medical, and narrative resources—whether exoteric, esoteric, or other—Yōsai thought to have the greatest therapeutic potential against rampant demonic disease during the age of the Final Dharma in which he lived.