Abstract
In The Metaphysics of Light in the Hexaemeral Literature, Isidoros C. Katsos explores the concept of light in early Jewish and Christian exegesis, particularly focusing on the hexaemeral literature—commentaries on the six days of creation as depicted in Genesis. Spanning figures from Philo of Alexandria to Gregory of Nyssa, he boldly challenges the prevailing scholarly view that ancient discussions of light were primarily “oculocentric,” focused on vision and perception. Instead, Katsos proposes a “luminocentric” perspective, asserting that light, rather than sight, was understood as the fundamental metaphysical principle integral to creation and divine revelation. Beginning with the sun-simile in Plato’s Republic, Katsos suggests that the question of light in ancient literature—at once physical, philosophical, and theological—is entangled with deeper questions of being and language.
Katsos narrows his focus to the metaphysics of light in the so-called Alexandrian Tradition, with Philo of Alexandria, Origen, Basil of Ceasarea, and Gregory of Nyssa as his primary interlocutors. He argues that these exegetes viewed light as both a physical and metaphysical phenomenon. Physically, light was associated with fire, the first material element; metaphysically, it represented the first immanent form of creation. This duality allowed early thinkers to bridge the divide between the sensible and intelligible worlds, using light as a means to contemplate the divine.
Katsos engages metaphor theory through Boyancé to pose a critical question, “What are the physical properties of light that are theologically relevant?” (10). If we fail to attend to the material features of light, Katsos rightly points out, theological claims about light as a symbol of the divine risk becoming empty abstractions (11). He thus begins with the assumption that the “concept of physical light grounds the referential meaning and semantic context of the theological language of light in early Christian literature” (13). His inquiry is not merely how these authors used light (literally, metaphorically, or anagogically), but what they thought light actually was.
Chapter 1, “From Sight to Light,” introduces Katsos’s central question: can we meaningfully speak of a physics of light in ancient hexameral literature? Katsos first considers the oculocentric paradigm—in which there is no ancient theory of light separate from a theory of vision—in Genesis 1:3-5, which describes the creation of light prior to the creation of human observers. Katsos considers the possible alternative viewers to the light of creation: angelic, celestial, and Christological. Drawing on the Platonic theory of vision—in which the eye mimics and receives external light—Katsos argues for a paradigm shift: from a world ordered around vision to one illuminated by the logic of light itself. He argues that when read alongside the Platonic theory, suddenly the “oculocentric hexaemeral world is transformed into a luminocentric universe” (53). Thus, the ancient Christian discourse on light, rooted in biblical exegesis, belongs to a broader late ancient physics of light. In this luminocentric view, Katsos argues, there must be a premodern physics of light that is logically prior to a physics of sight.
Having established his luminocentric paradigm, Katsos turns to the scientific and theological stakes of that shift in Chapter 2, “The Light of the World.” Katsos first argues that the biblical creation narrative offers a framework for scientific inquiry that exegetes are meant to uncover and contextualize. He then explores how Origen shaped hexameral physics through a combination of exegesis and apologetics in response to Platonizing critics of Scripture like Galen and Celsus. Origen, Katsos argues, “could appeal to the metaphysics of the Phaedo to score a point from within the same school of thought” (75). By linking divine omnipotence to material processes, Origen set the stage for Gregory of Nyssa to further develop the implications of a physics of light rooted in Scripture. Light, connected to fire, becomes a bridge between physics and metaphysics. In this way, “The hexaemeral physics of light served simultaneously a double purpose: biblical apologetics and scriptural hermeneutics” (108). The hexameral physics of light not only portrays the consistency of Scripture with science, but it also reveals that the logos was integral in all stages of creation.
In Chapter 3 “The Nature of Light,” Katsos further explores the physical and metaphysical nature of light, focusing on its link to fire and its role as a boundary between the material and the immaterial. Katsos engages this liminal space—through a combined reading of Basil of Caesarea’s Homilies and Gregory of Nyssa’s Apology—to produce a systematic theory of hexaemeral light along three axes: the substance of light (‘fire’); the emission of light (‘radiant light’); and the effects of light in space (‘ambient light’). These features, Katsos argues, reveal a consistent interpretive thread from Philo (faintly) to Origen and ultimately Basil and Gregory of Nyssa that interprets the light of Genesis as the immanent manifestation of the logos in creation. Light, as both a natural phenomenon and a symbol of divine reason, becomes a key to understanding how the logos is embodied in the world. Thus, the beauty of physical light stirs wonder and points to its deeper intelligible source, grounding a theological vision in which creation itself discloses the logos.
In his Conclusions, Katsos returns to the significance of the Timaeus in hexameral literature and then turns to the implications of his study. He notes, “In the eyes of the contemplative reader, the hexaemeron is transformed from a cosmological narrative into a literary mirror of the world in which the human mind can contemplate its own reflection” (170). By reading scripture with the creation of light on day one, the reader starts the journey “that leads from the light of the world to the emergence of the human species… and the formation of the human self” (170). But Katsos’s study of light not only leads to contemplation of the world, but also to contemplation of “the divine mind that conceived it, namely the demiurgic aspect of its logos” (172). Katsos ends, “To the Christian readers, this is a vision of Christ as the heart of creation… The aim of the metaphysics of light in the early hexaemeral literature is the attainment of a vision of Christ, the embodied logos, as the metaphysical foundation of Moses’ philosophy of nature” (174).
After the Conclusions, Katsos includes three Appendices. Appendix A offers a direct response to Mark A. Smith’s critique of Katsos’s claim of a premodern physics of light that is separate from sight. Katsos notes their divergent interpretations of Timaeus and reflects on the nature of epistemic humility. If Katsos and Smith can have such different readings of Timaeus, then it is even more likely that the hexameral authors might have read the same text differently as well. In this way, Katsos encourages his readers to hold open the idea that there was a premodern physics of light. If not in Plato’s text itself, then perhaps one existed in later interpretations of it, such as the hexameral tradition. In Appendix B, Katsos grapples with ancient views on the color of light. Appendix C analyzes the various uses of doxa by Gregory of Nyssa for the brilliance of light.
Katsos’s work has many strengths. The first is its interdisciplinary focus, drawing together the history of science, philosophy, and theology to reveal the interplay between classical philosophy and early Christian theology. Katsos does not merely read patristic texts; rather, he reconstructs a conceptual world in which light was both physical and metaphysical, scientific and theological. The second strength is Katsos’s bold challenge to prevailing scholarly assumptions. Katsos invites his readers to look past the oculocentric view to imagine another focus: one that starts with light. This reframing invites the reader to reconsider the metaphysical significance attributed to light in early theological thought. By entering this premodern thought world, the reader gains new insight into how light functioned by first reflecting on the nature of that light. In doing so, Katsos reveals light’s Christological and anagogical significance.
Yet I also have a few suggestions. Katsos is at his best when he reflects on the significance of his careful analysis, which leads to some delightful insights. But he also occasionally veers into overextended technical discussions that obscure rather than illuminate his point. Some of those excursuses have been shifted to the Appendices, but perhaps a few more of the technical detours would have been better placed in the appendices as well. More significantly, Katsos tends to set up a rigid binary between oculocentricism and luminocentricism, implying a hierarchy in which the latter supplants the former. In the context of contemporary debates, he offers a dramatic reversal: no longer from sight to light, but now from light to sight. Yet, in Appendix A, he reveals that he first thought of the two as complementary approaches (175). I would have liked to see this integrative nature drawn out more in the body of the text. After all, vision and light both function in different but related ways in the hexameral literature, so highlighting their interaction, rather than opposition, would have enriched the analysis.
One additional concern relates to Katsos’s claim that the hexameral authors uniformly adopted a Platonic theory of vision. He writes, “For the hexaemeral authors, who, like many of the natural philosophers of their time, adopt the luminocentric premise of the Platonic visual paradigm, oculocentricism is a position very difficult to uphold” (53). However, Gregory of Nyssa, for example, describes sight in distinctly atomistic terms in his Homilies on the Song of Songs 4.1, writing, “for people who can give the scientific explanations of such things say that the eye activates its vision by receiving the impressions of the images [τῶν εἰδώλων ἐμπτώσεις] given off by visible bodies” (Cant 4, 117). If Katsos’s rejection of the oculocentric view depended solely on the assumption that each of these authors adhered to a strictly Platonic theory of vision, then his entire argument would crumble. That said, I do not think that it does. Were he to adopt a more nuanced account—one that allows for light and vision to operate in complementary but distinct ways—then his technical analysis of light and his significant conclusions would likely still stand. Still, in light of both Smith’s critique of Katsos’s reading of Plato and my own concerns about his wholesale application of that reading to the hexaemeral corpus, I would have liked to see a careful engagement with the scientific frameworks found within each author’s text. Exploring these various scientific assumptions likely would have revealed some key differences among the authors that would have been fascinating to explore alongside the thread of commonality that Katsos draws among them.
In the end, Katsos’s work is a fascinating read for those in theology, philosophy, and the history of science. His bold challenge to prevailing scholarly assumptions is worth taking seriously, particularly for the insights he draws out in the thought world of the hexaemeral authors. His work points us to a missing thread—the physics and metaphysics of light in the hexameral authors—and offers a fantastic starting point for us to begin to tease out the relationship between sight and light in ways that have not yet been done.