Light is present, yet who sees it in itself? It is the condition for everything it is notâfor the visible, for being, for life, for thought. Luminous phenomena are immanent to sensible apprehension while light remains wholly foreign to everything that it reveals. Knowing it requires that one grasp its effect, at once singular and manifold, through the infinite unfolding of the visible and the living. âThis stone is light to meâ (lapis iste ⦠mihi lumen est), said an Irish philosopher situated at the crossroads of Late Antiquity and the Middle Ages. It is by seeing that the eye recovers the power of the fiat lux: the eye constitutes visibility as the universal expression of being, while at the same time allowing light to be disclosed as the transcendent condition of appearing.
Plato, Aristotle, and Plotinus evoke light by speaking of the kind of touch that defines sight. It is the most immediate sensible experience that leads to the apprehension of light as a principle of life and a condition of knowledge. At the dawn of premodern history, two of their later heirs, Dante and Marsilio Ficino, describe light as that which stands beyond appearances, and yet determine them. Prior to Kepler and Newton, light is irreducible to a merely physical phenomenon. To grasp the stakes of this aporetic status, whose consequences are foundational for philosophy, let us read once again the Timaeus, the Republic, the Phaedrus, the Symposium, Aristotleâs De anima, as well as some of Plotinusâ treatises.