Illuminating Causality: The Role of Light in Thomas Aquinas’s Metaphysics of Being

Abstract

In this article, we hold a strong thesis, i.e., that light is the conceptual resource that best explains the creative act in Thomas Aquinas’s metaphysics. Thus, inasmuch as being is the luminous act of the Uncreated Being, it bears resemblance to the Uncreated Being in its very principle. In this sense, we seek to present the role of light, in its meaning as manifestation, as an act that belongs to being. Indeed, in contrast with some contemporary interpretations, which place light within the order of formal causality, we argue that light, in its belonging to Aquinas’s participatory metaphysics, pertains to the order of efficient causality. Therefore, we hold that light has strong explanatory pretensions in Aquinas’ thought. Accordingly, after an introduction (1), this article is divided into the following sections: (2) The Meaning of Divine Causality; (3) Being as Light; (4) The Manifestative Character of Light; (5) Light Images: Analogies and Metaphors; and (6) Conclusions.

1. Introduction

In what is now a classic text on metaphysics, Etienne Gilson (1961) affirms that one of the central aspects of Thomas Aquinas’s reformation of metaphysics is that he introduces a “clear-cut distinction between the two orders of formal causality and of efficient causality” (p. 168). In this sense, according to Aquinas (2012), substance is actualized as a determination of being, which is “the actuality of all actualities, and for that reason the perfection of all perfections” ([QDP] 7.2. ad. 9). Therefore, being itself is the principle of every created act and that in reference to which form communicates its actuality to the substance (QDP 5.1. Resp.). Taking this into account, the French author states that efficient causality entails the communication of “existential being to substance” (p. 169). In fact, as one can see from Aquinas’s affirmations, substance, which pertains to the order of formal causality, is actualized as a reality that participates in the potency of being, which pertains to the order of efficient causality.

Moreover, the Angelic Doctor situates God’s causality as the origin of the distinction between those two orders. In this sense, the production of being by the Uncreated Being (Aquinas 2024a, [ST] 1.45.4. Resp.) as a relational act (ST 1.45.3. Ad. 3) leads to the constitution of the substance, which is actualized by virtue of the potency of being (ST 1.45.2. Ad. 2). Therefore, creation is formed within a participatory dynamic in which the formal order “takes part” (Aquinas 2001, [In BDH] Ch. 2) of the efficient order.

Additionally, the participatory dynamic of creation is given under a luminous horizon (Aquinas 2001, In BDH Ch. 2), within which, primarily, the efficient order of divine causality is actualized and, secondarily, the formal order. Thus, far from being reduced to the formal order of divine causality, light also is actual in the order of efficiency, giving being a manifestative character (Aquinas 2024a, ST 1.67.1, resp.). Hence, the communication of being is accompanied by the radiance or luminosity that, in its condition of pure light, the Uncreated Being communicates to being. As Aquinas (1963) affirms, the participatory situation of being entails the reception of a light communicated by the Uncreated Being (Aquinas 1963, [DSS] Ch. 3). One can say, then, that Aquinas’s metaphysics belongs to what James McEvoy (2000) has aptly termed “the metaphysics of light” (p. 91).

Nevertheless, light’s metaphysical potency has been more frequently studied in the formal order of divine causality by different contemporary interpreters (Fabro 1961; Kieninger 1990; Boland 1996; Doolan 2008; Cuddeback 2009; Whidden 2014). This has led to the reduction in the Thomistic metaphysics of participation to the formal order of causality.

In response to this set of interpretations, some studies have recently been published, which, recognizing the participatory situation of being, locate the Thomistic metaphysics of participation in the order of efficient causality. In this sense, Patrick Zoll (2022) integrates the participatory dynamics of being under this order (pp. 138–39), although he leaves aside the centrality of light in the development of the participatory dynamics of being under the order of efficient causality. Likewise, Isidoros Katsos (2023) recognizes the metaphysical shaft of light in the metaphysics of Aquinas (p. 160), but his study is directed to the study of light in the framework of the Hexaemeral tradition, shaped by the Fathers of the Church.

These two scholars correctly interpret the aspects of Thomas’s thought toward which their studies are directed. However, Zoll (2022) avoids referring to the importance of light in Aquinas’s metaphysics of participation, while Katsos’s (2023) study is directed towards the research of light in the Patristics.

Taking all of the above into account, we affirm that light is the conceptual resource that best expresses the creative act in Thomas Aquinas’s metaphysics. Thus, “God is light” (1 John 1:5), not “in some metaphorical or poetical sense” (McEvoy 2000, p. 91) and creation participates in Him, possessing, then, a luminous actuality. In this sense, we hold a strong thesis, i.e., that the Angelic Doctor’s metaphysics of light entails a conception of being as a luminous act in its coming from the Uncreated Being and in its resemblance to Him. One can say, then, with James McEvoy (2000), that, according to Thomas Aquinas’s metaphysics of light, “[the] whole of being is light, since absolute Being and absolute Light coincide and are but one” (p. 91).

Having, thus, introduced the main thesis of the article, we will develop the following sections: (2) The Meaning of Divine Causality; (3) Being as Light; (4) The Manifestative Character of Light; (5) Light Images: Analogies and Metaphors; (6) Conclusions. For doing this, we will employ a methodology of discussion with contemporary interpreters and, simultaneously, we will develop a systematic approach to the deep meaning of Aquinas’s metaphysics.

2. The Meaning of Divine Causality

Aquinas’s metaphysics of light has its foundation in a conception of divine causality according to which God creates being “as the direct participation” (Clarke 1994, p. 7) of His own perfection. Thus, in its actuality as true light, God communicates light to being, which finds itself in a participatory situation with respect to Him. Light or manifestation (Aquinas 2024a, ST 1.67.1. Resp) is, thus, actualized as an intelligible attribute of being (Aquinas 2010, [In Io] 1.1.3) in virtue of being’s metaphysical dependency towards God. Therefore, being, which is “the root of intelligibility itself” (Clarke 1994, p. 7), is a manifestative act.

Hence, there is a sense, the most fundamental one, in which divine causality can be explained as the production of being; Aquinas (2024a) refers to this causal moment of God’s operation as efficient causality (Soto-Bruna 1994, p. 33). This causal moment alludes to the instant where there occurs “the emanation of the totality of esse” (ST 1.45.1. Resp.), where esse is “the first effect of divine operation” (ST 1.45.5. ad. 1). Thus, turning to the Platonic semantics of emanation to explain God’s efficient causality, Thomas points out that creation emanates from the divine communication of being, where emanation alludes to the continuity of cause and effect. This continuity is expressed in the manifestation of the cause in the very constitution of the effect through the principle of similitude, i.e., the axiom according to which each agent makes something similar to itself (Aquinas 2012, QDP 9.5. ad. 18).

Accordingly, in the creative act, the Uncreated Being prints over being a similitude with Him, giving it “an ‘efficient’ likeness” (Pierson 2022, p. 526). In this sense, Aquinas (1957) affirms that because of God’s creative act “all creatures are nothing but a kind of real expression and representation of those things which are comprehended in the conception of the divine Word; wherefore all things are said” (Aquinas 1957, [SCG] 4.42). Thus, according to the Angelic Doctor, the being’s participatory situation in regard to its first principle is indicated by being’s condition as an ‘expression’ and ‘representation’ of the Uncreated Being. Commenting on this situation, Zoll (2022) refers to participation as a “certain likeness or similitude which its intrinsic esse bears to subsistent esse itself as its cause” (p. 211). One can say, then, in virtue of the principle of similitude, that God, which is represented and expressed in the whole of creation, is manifested in being and in its determinations.

In this sense, by communicating being a constitutive light (Soto-Bruna 1996, p. 1041), God gives it its manifestative character. Thus, Aquinas (2010) affirms that “in whatever the name ‘light’ is used, it implies a manifestation, whether that manifesting concerns intelligible or sensible things” (In Io. 1.1.3). Moreover–Aquinas continues–“if we compare sensible and intelligible manifestation, then, according to the nature of things, light is found first in spiritual things” (In Io. 1.1.3). Thus, in its primary meaning, which controls its secondary meanings (McInerny 1996, p. 114), light refers to the manifestative character that is actualized fundamentally upon the metaphysical order and subordinately to this, upon the sensible order. Indeed, light actualizes itself upon being before doing it over the being’s sensible determinations. Consequently, the manifestative character of which light is the bearer, crosses the entire creation, belonging with all propriety to the intelligible order and contracting, as it were, to the sensible order; light, then, “crosses the whole space of being” (Castro 2021, p. 9).

To explain how light crosses the whole space of being, one could allude to Stump’s (2016) idea of Aquinas’s metaphysics as a quantum metaphysics. In fact, she integrates Aquinas’s conception of divine causality within the framework of a bold explanation regarding quantum light (p. 200). In this sense, through her allusion to quantum physics, one can explain the situation of being as light since, according to Aquinas’s conception of divine causality, God is the first causal principle; hence, He is the cause of being’s actuality and luminosity, without reducing Himself to it. Moreover, as was previously said, God’s operation simultaneously extends to being and to the determinations that follow upon it.

In this order of ideas, in line with Stump’s allusion to quantum light, the consensus among physicists today is that there is certainly, as far as light and electromagnetic radiation are concerned, a duality in it as a wave and as a particle. As a wave, light manifests itself in interference and diffraction; on the other hand, as a particle, it manifests itself in emission and absorption, although there is no consensus among physicists on the meaning of this reality at the ontological level (Henriksen et al. 2018, p. 94)1.

In this sense, one could affirm that the dual nature of light as a particle and as a wave allows one to better understand how is it that God’s causality—heuristically speaking—as a particle and as a wave, is actualized upon being and its determinations. Indeed, it operates as a particle when He produces being and as a wave when His causal power extends to the determinations that follow upon being. This dual nature of light serves, then, to maintain that, as a source of light, the Uncreated Being is the principle of being. Therefore, He is the first principle of the luminosity of being, and, simultaneously, His causal power extends to all the metaphysical determinations of beings. These are also luminous by participating in the light of the Uncreated Being. Thus, light, in its specifications as a particle and as a wave, operates similarly to God as the principle and cause that becomes present in its effects; indeed, He is actualized, by means of His causal power, in being and in the determinations that follow from it. Indeed, just as in the “quantum world, light is neither ‘here’ nor ‘there’, but ‘here-there’”, as a “wave-particle” (Katsos 2023, p. 55). Similarly, God creates the “particle”, i.e., being, and His causal power extends, “as a wave”, to the metaphysical determinations of beings.

The aforementioned presence of God in His effects entails the participatory situation of being in relation to Uncreated Being. By virtue of this, there is a circular relationship between cause and effect, where the perfection of divine operation becomes evident in the perfection of its effect; there is, then, a relationship of similarity, resemblance or likeness of being with respect to Uncreated Being. In this sense, the first effect of divine causality, being, is constituted primarily as a participatory act in its orientation towards its cause and, secondarily, it is constituted in virtue of its internal metaphysical determinations, which it possesses in itself. In this sense, one might characterize Aquinas’s account of divine causality as God’s communication of light to being. In virtue of this communication of light, one might characterize Aquinas’s metaphysics as a “metaphysics of participated actuality” (Hibbs 2007, p. 136).

Following this participatory conception of being, one can observe the inspiration that Thomas Aquinas receives from Plato. In this sense, his metaphysical thought is nourished by the Platonic sources to which he has access, such as the works of Dionysius the Areopagite and the author of the Elements of Theology. He, thus, follows Plato’s participatory account, which considers that there is an orderly relationship between the whole and the parts. In fact, according to Plato, the parts, which are equidistantly related to each other, are oriented to the whole. This orderly relationship arises from the constitutive likeness or resemblance that lies at the fundamental core of creation (Cf. Plato 1997, Timaeus, 33b–c).

In agreement with this line of reflection, the Angelic Doctor affirms:

“because all things are in him [God], as comprehending all things in himself, ‘at the same time’, ‘all things are predicated’ of him and at the same time all things are removed from him, because ‘he is none of them’, but above all; as it is said that he is ‘of every shape’, inasmuch as they all pre-exist in him, and yet he is without shape, because he does not have being in the mode of things that are shaped; and for the same reason he is of every beauty and yet ‘without beauty’, inasmuch as he ‘incomprehensibly and exceedingly’ precontains ‘in himself the beginnings and middles and ends’, not by any corruption, but from the fact that he ‘as one’ unity pours out ‘being over all things’, shining over them without tainting himself: for he is not altered while altering [other things], as happens in bodies”.

(Aquinas 2021, [In Div. nom.] 5.2.661)

Hence, according to Aquinas’s participatory metaphysics, beings, secundum re, pre-exist in God. They have a figure, which manifests the model, where the latter contains them in Himself precisely in virtue of His infusion upon them of a fundamental resemblance to Him. This resemblance manifests itself in the internal order of beings and in the order that is given among beings. In this sense, the universe receives from the Uncreated Being its principles, its intermediate realities and the ends toward which it is oriented as an orderly determined whole.

Thus, in the orderly relationship between these three determinations: the principles, the intermediate realities and the ends, the divine causality is manifested in creation. In effect, the power of the sun is manifested in its unifying capacity, through which the illuminated realities share among themselves the brightness that the sun infuses upon them; moreover, it leads them to relate to each other in multiple ways. Analogically, the Uncreated Being’s causality leads the intermediate realities and ends to be reduced to being as their principle of unity. As Aquinas (2021) asserts, “nothing can be called a being unless it has being” (In Div. nom. 5.2.659). Indeed, nothing is an id quod est without being, in the first place, actual in virtue of the power of the ipsum esse, which is a participative light that is projected onto everything that is. Consequently, one might say that Aquinas’s conception of divine causality results in a metaphysics of participated actuality in which plurality is always oriented towards unity (Wippel 2000, p. 95); in this, he follows the Platonic tradition in line with Plato’s Timaeus.

3. Being as Light

Taking the above into account, it has been shown that Aquinas situates the principle of creation in the Uncreated Being’s causally efficient power. In fact, the Uncreated Being communicates to the creation the power of its fundamental light, giving beings their resemblance to the Uncreated Being, which is “pure light” (Aquinas 1996, [In CA.] Prop 6). In this sense, God produces being itself, conferring upon it “the very actuality”, which, thus, constitutes, “in certain way”, the being’s “light” (In CA. Prop. 6). Therefore, appealing to the image of light, which has, in this context, an analogical import, Aquinas (2021) considers that the light or manifestative character of being is the very principle of the brilliance or “shining” of creation (In Div. nom. 5.2.661).

In this order of ideas, Thomas Aquinas (1957) explains the participation of being, i.e., its condition as a created and luminous act, as the principle of the beings’ determinations. Thus, he affirms that “God alone is essentially a being, whereas all other things participate in being”, from what follows that “every created substance is compared to its own being as potentiality to actuality” (SCG 2.53). In this regard, “being itself is compared to all created substances as their act” (SCG 2.54), and, therefore, “being is the act of that whereof we can say that it is” (SCG 2.54). In other words, form is “that by which [being] is”, since “being itself is that by which the substance is called being” (SCG 2.54). From this it follows, first, that “neither is the form the being itself, but between them there is a relation of order, because form is compared to being itself as light to illuminating, or whiteness to being white” (SCG 2.54). Second, it follows that being is related to form as “light” is related to “transparency”, while form is related to substance as “transparency” is related to “air”. In fact, as “transparency” “makes the air the proper subject of light” (SCG 2.54), the form makes the substance the proper subject of being.

According to the above, it can be observed that Aquinas’s metaphysics of participation begins from the consideration of the operation of the Uncreated Being, which is simple in virtue of the identity in Him of being and essence. Thus, the participatory situation of being, which emanates from the Uncreated Being, entails that being is effective in the determinations that follow from it, communicating its actuality to the entity. In this sense, being is actualized upon both form and substance, which are determined by being, through the influence that it exerts upon them. For this reason, being is the act of that which is, instantiating itself in the substance under the determination imposed on it by the form. Therefore, the form constitutes the medium through which being actualizes the substance.

In this sense, being, like light, is actualized on its determinations, leading to their articulation toward it as the principle of their unity. Thus, the determinations of being are ordered toward it since it is the first actual principle of what is. Moreover, just as light leads transparency to actualize itself as such by shining upon it, so form is subsidiary, as it were, to the actuality communicated to it by being. In consequence, just as light collapses upon air by the transparency that leads air to be able to receive light, so being is actualized upon form in order for a substance to receive being through the influx of form.

In this line of reflection, creation can be understood as a luminous whole within which, speaking through images, there is a polychrome of tonalities, where the luminous power of being transverses all the determinations that conform beings. In other words, the participatory luminosity of being shines over form and substance, communicating them their actuality. For this reason, one could say with Thomas that the operation of the sun is an image of the creative operation of God. In fact, just as during illumination “a thing is simultaneously being illuminated”, while “it has been illuminated” (Aquinas 2024a, ST 1.45.2.3), the “being made (fieri)” of the being is simultaneous with its “having been made (factum esse)” (ST 1.45.2.3). Certainly, the beings are both produced and sustained in being by the light of divine causality, which entails that being is a dynamic act (Cf. Gilson 1961, p. 184; de Finance 1965, pp. 250–51; Clarke 1994, p. 9; Pierson 2022, p. 530); hence, being develops in the pace of the permanent illumination exerted upon it by the Uncreated Being. Taking this into account, being, which is the first act and light of beings, is actualized in them with such power that it extends itself over all their determinations, communicating them a manifestative character.

4. The Manifestative Character of Being

It is in the context of this account, in which being possesses a manifestative character, that Aquinas characterizes being as an expression (expressio) and as a representation (repraesentatio) of the Uncreated Being (Aquinas 1957, SCG 4.42). Indeed, in virtue of this participatory account of being, one could say that being is a light or manifestation, which expresses and represents God’s light.

In its expressive instance, being shines over the whole of creation, including its intermediate realities and ends (Aquinas 2021, In Div. nom. 5.2.661) and gives creation a likeness or resemblance to the Uncreated Being. In fact, in virtue of its expressive determination, being has a resonant effectiveness on all that is. For this reason, it bears a relation of resemblance or likeness to the Uncreated Being and in its very principle it bears the character of a relational structure in which being illuminates its determinations; due to this illumination, beings manifest themselves to each other. Consequently, through the brilliance that being expresses and communicates to all beings, they are constituted as relational acts.

Now, in his allusion to being as a representation of the Uncreated Being, the Angelic Doctor also shows that being is a production that is determined by the Uncreated Being as an image. In this sense, being represents its model, Uncreated Being, to the extent that it has some perfection (Aquinas 2024a, ST 1.13. Resp), from what follows that in its actuality as an image, being represents the perfection of the Uncreated Being with a certain degree of clarity. Therefore, Uncreated Being dwells in being, which is the very principle of the universe. In this sense, the Uncreated Being is permanently manifested, both in being and in its determinations, for it sustains being in its existence (Aquinas 2024a, ST 1.104.1. Resp.).

However, against the interpretation that has been put forward concerning Aquinas’s metaphysics, David Bradshaw (2004) states that in its reliance on efficient causality, Thomas’s account of “the participation of creatures in God” leaves “the relationship between God and creatures merely extrinsic” (p. 257). As a result, according to Bradshaw, in Aquinas thought there is “a certain sense of distance between God and creatures” (p. 268). For this author, it seems to follow that, according to Aquinas, being would only be incidentally related to the Uncreated Being. In effect, according to Bradshaw’s interpretation, the Uncreated Being would let everything develop within the framework of being’s own efficacy. The development of being would be, then, in itself and for itself. In this sense, under Aquinas’s theory, creation would be autonomous to a high degree and, therefore, it would be difficult to elucidate how is it that God operates within being, since divine operation would only be incidentally actualized in creation.

Nevertheless, this interpretation of Thomas’s metaphysics is incorrect. In fact, Bradshaw avoids referring to the centrality of light or the manifestative character of being in Aquinas’s metaphysics. In effect, although Uncreated Being operates efficiently upon being by creating it, and gives it its own actuality, being is never radically detached from its first principle, namely, the divine causality. This is so, because being, with its manifestative character, is the inmost act of every being, from what follows that, in producing being, Uncreated Being becomes present at the core of every created act. According to Aquinas (2021), being is never in itself and for itself because its actuality comes from the Uncreated Being, which creates being as a “mirror” in which “the image of the one seeing, i.e., the Uncreated Being, is represented” (In Div. nom. 4.18.524).

5. Light Images: Analogies and Metaphors

The aforementioned manifestative character of being indicates that the way in which Thomas employs light and light images is not merely incidental or dispensable in his metaphysical explanations (McEvoy 1978, p. 141). In this sense, his recourse to light has explanatory pretensions concerning the participatory situation of being in relation to the Uncreated Being, insofar as it accounts for the situation of resemblance between them. Just as light manifests its source, i.e., the sun, so being manifests its source, namely, the Uncreated Being.

In this sense, one of the features that makes light a complex reality is that it is actualized in the metaphysical order, but it also is actualized on the sensible one. This implies that, having a fundamental meaning, the term can be used to signify different aspects of the same reality, as Aquinas (2010) affirms in the Commentary of the Gospel on John (1.1.3). Indeed, the polysemy of the term is based on the complexity of the reality to which it refers, since being marks the paradigm of meaning.

However, “light”, which refers to a multifaceted reality, is not merely an equivocal term, since, according to Aquinas’s theory of analogy, there is always a primary meaning that controls the subordinate meanings of a word. Indeed, although complex terms have “several senses, still [they are] not predicated equivocally but in reference to one thing” (Aquinas 2011, In Met. 4.1.536). In Ralph McInerny’s (1996) words, “the proper meaning of the term, its ratio propria, is found in only one of the analogates and the others are named with reference to, by proportion or relation to, it” (p. 114). In this way, complex terms are analogical because, while keeping the reference to a defined reality, the irreducibility of the reality to which they refer leads the intellect to form a plurality of meanings with respect to it. Consequently, the Thomistic theory of analogy entails that “light” can be signified under multiple meanings, where the primary one is manifestation, for as the fundamental note of light, manifestation, is common to both, its intelligible and its sensible determination (Cf. Aquinas 2024a, ST 1.67.1. Resp. and Aquinas 2024b, In Sent. I 21.14.35).

Taking into account the complexity of light, Aquinas (2024b) carefully affirms, referring to different light images received from the Christian tradition, that “Indications of similitude are: splendor, letter of the alphabet, mirror, and suchlike” (In Sent. I 22.1.4). However, he seems to object to the idea that they allude to similitude or resemblance, “since, according to Augustine, light is more properly said of spiritual things than of bodily things, so ‘splendor’ is not contained among the metaphors” (In Sent. I 22.1.4). Nevertheless, he adds, “one should say that light, as regards the reality being signified, is properly in bodily things, nor is it in spiritual things unless it is being said metaphorically” (In Sent. I 22.1.4); thus, “as regards the account from which the name is imposed, which consists in manifestation, is it more properly found in spiritual things” (In Sent. I 22.1.4).

According to Aquinas, terms like “splendor”, “letter of the alphabet”, “mirror” and suchlike are under the paradigm of similitude, likeness or resemblance, since as images of light they indicate in one way or another a certain manifestative character. Thus, Thomas agrees with Augustine that these images can be properly predicated of intelligible realities. However, he reformulates the thought of the Latin Father by affirming that these terms can also be predicated improperly of intelligible realities, i.e., metaphorically, when they allude properly to light as the sensible reality that the physical sciences study. Consequently, Aquinas reformulates the theory of Augustine, stripping away the ambiguity that this conception of the meaning of the term “light” might entail (McEvoy 1978, p. 141).

Thus, under the use of the term in its sensible determination, when it refers to intelligible realities such as God, being or intellect, Aquinas (2024b) asserts that light is used metaphorically. In this sense, in its metaphorical use the term is oriented to “a certain effect” of an intelligible reality (In Sent. I 45.1.4). Now, and in this respect, Thomas follows the Platonic tradition, when the term alludes principally to manifestation, then light is properly predicated of intelligible realities.

In this sense, when the term “light” refers to the sensible order it is restricted to a physical reality and can only be predicated metaphorically of intelligible realities. Nevertheless, when it refers to the intelligible order it indicates manifestation and can be contracted to signify a sensible reality. Indeed, manifestation directly alludes to the spiritual or intelligible order, but it also emerges in the sensible order, for things are sensibly manifested. Thus, alluding to manifestation in the sensible order, Aquinas (2021) affirms that although “the light of the sun cannot be looked at by us in the sun itself on account of the excess of its light”, “it is seen in beams coming forth from the sun in the clouds or in the mountains” (In Div. nom. 4.1.287). Therefore, “clouds or mountains manifest to us the brightness of the sun” (In Div. nom. 4.1.287).

According to the Angelic Doctor, human beings see the light of the sun in the clouds and in the mountains, for they cannot see it directly in the source from which it comes, namely, the sun. Thus, by virtue of the brightness of the sun, its light manifests itself to them, showing itself by reflection in those things on which the sunlight rests. Consequently, sensible manifestation entails the actualization of the sunlight on a certain surface, from which the sun is manifested by reflection to the viewer. In this sense, it can be said that the relation of light to the sun is similar to the relation of being to the Uncreated Being, since the illuminating power of the Uncreated Being manifests itself in being by reflection, just as the sun manifests itself in the light that is reflected on certain surface.

Following this same line of thought concerning light images, one can bring to mind the aforementioned metaphor of the mirror (Cf. In Div. nom. 4.18.525; ST 1.56.3. Resp.). Although the context under which Aquinas employs this metaphor is an explanation of the angel’s being, which resembles, in its perfection, the divine goodness, this metaphor can be transferred from metaphysical reflection in relation to the angel to metaphysical reflection concerning the resemblance of being to the Uncreated Being. Thus, it can be said that, in its manifestative character, being keeps with the Uncreated Being a mirror relation, in which the Uncreated Being itself is manifested in the metaphysical constitution of being.

In this sense, Aquinas (2021) affirms that, in its situation as a specular act of God, being is somehow “godlikeness”, because it is impossible that “the whole beauty of God be received in any created mirror; but in some created mirror, on account of its purity and clarity, the whole beauty which is possible to be in a creature by a likening to God is perfectly received” (In Div. nom. 4.18.525). For Aquinas, the resemblance of being to the Uncreated Being refers back to the very act in which the Uncreated Being creates by communicating being. In this sense, divine causality does not only consist in creating being from nothingness. In fact, as can be seen from the influence exerted by Dionysius on the Angelic Doctor, a full understanding of divine causality must be articulated in the horizon of light, since this is the path taken by Aquinas to explain the participatory situation of being.

Indeed, Thomas Aquinas (2024a) emphasizes, in the first place, the impossibility of being to receive completely in its constitution the beauty of the Uncreated Being. Thus, he adds that, nevertheless, being receives beauty proportionally to its capacity to do so; this, in virtue of its clarity (ST 1.39.8. Resp.). Thus, appealing to the metaphysical note of clarity, which, together with the metaphor of the mirror, is one of the images of light, Thomas situates beauty as an intelligible note of being. Consequently, the specular situation of being, which is luminous by virtue of its participative constitution, entails that God’s efficient causality is a communication of light (cf. Monachesse 2016, p. 222; O’Rourke 2019, p. 98; Ramos 2012, p. 73). In this sense, the participation of being in the Uncreated Being is a determination which, by way of light, will establish itself as the principle not only of the actuality of being, but also of its luminosity. In other words, being is an act specified under the manifestative character to which the primordial meaning of light alludes.

In this regard, appealing to Dionysius, Aquinas (2024b) says that “just as the sun sends forth its rays to illuminate bodies, so also the divine goodness diffuses its rays, that is, participations in itself, in order to create things” (In Sent. II Prol.). In fact, Thomas compares the collapse of sunlight on sensible bodies with the divine illumination of beings. In this sense, the light images allow him to explain that each being and the whole of beings are in a participatory situation, which is the first determination of being.

As a conclusion to this section, it can be said that in Aquinas’s metaphysics, the production of being conflates with its participatory situation. According to the Angelic Doctor, every created act and, in particular, the first of created acts, namely, being, is accompanied with the note of luminosity or manifestative character. In consequence, creation, analogically speaking, is a communication of light.

In virtue of its participative situation with respect to Uncreated Being, being is rich and perfect, for it is actual, first of all, in its resemblance to Him, which possesses with eminent perfection all the determinations that unfold in creation. Inasmuch as being and its subsequent determinations are likenesses of the Uncreated Being, God rests at the core of the metaphysical constitution of all created acts, giving them beauty; He rests in being and in its determinations without reducing Himself either to it or to them. In this sense, in its participative status, being “announces” Uncreated Being, since “that which something has participatively and in a secondary way is an ‘image’ of that which has it in a primary way and causally” (Aquinas 2021, In Div. nom. 4.18.522). Thus, in its situation as an image, the act of being is “to manifest that of which it is the image” (Aquinas 2021, In Div. nom. 4.18.522). In this way, being manifests the Uncreated Being, since the image keeps with the principle a relation of resemblance that is expression of its situation with respect to Uncreated Being.

6. Conclusions

In this article, God’s efficient causality was explained from the framework of light, not only as the production of the act of being, but also as the production of an act of being that is luminous in its very principle. In fact, according to Aquinas, the scope of the meaning of ‘light’ is deeper than an exclusively metaphorical determination of that term would entail. Consequently, light constitutes a complex reality with a profound significance in its explanatory pretensions concerning different issues at stake in the Thomistic theory of participatory causality and being.

Likewise, this article seeks to have opened the way to investigate, through recourse to the analogy of light as manifestation, how the primacy of being as the luminous principle of all that is leads the determinations of each being to be actualized as participative instances of being. In this sense, the article was intended to strengthen the set of interpretations of Thomas’s metaphysics that emphasize his Platonism.

Finally, the article opens an innovative approach to understanding beauty. In this sense, insofar as light is in the definition of beauty, the latter is understood in the thought of Thomas Aquinas as a transcendental or intelligible determination of being. By this, we mean that light enters the definition of beauty; indeed, insofar as light refers to being and truth, beauty connotes a ratio intelligibilis, as Thomas affirms in chapter 4 of De Divinis nominibus. Beauty is, thus, associated with light, referring to the manifestative character of being. Now, to complete the intended conception of beauty as a transcendental attribute of being, there remains the task of investigating how other requirements of beauty, such as perfection and consonance, are part of the metaphysical constitution of being. Certainly, with this it will be possible to observe, under a broader picture than the one presented in this article, how beauty is specified in its transcendental status.