Phronesis 63 (2018) 209-210 brill.com/phro Note ∵ Color, Transparency, and Light in Aristotle Sean Kelsey Department of Philosophy, University of Notre Dame, 100 Malloy Hall, Notre Dame IN 46556. USA skelsey@nd.edu Abstract Aristotle says that it is in the nature of color to impart movement to transparent media. Typically this is interpreted as implying that these media must be transparent (in fulfillment) before color moves them. I argue that this is a mistake. Keywords Aristotle – color – transparency – light – nous – intelligibility – noēsis Aristotle says that it is in the nature of color to impart movement to transparent media: to media, that is, which are transparent, not merely potentially, but ‘in fulfillment’ (ἐντελεχείᾳ) or ‘in activity’ (κατ’ ἐνέργειαν) (DA 2.7, 418a31-b2, 419a9-11; cf. 418b11-13). Typically this is interpreted as implying that these media must be transparent (in fulfillment) before color moves them (so e.g. Johansen 1998, 67, Sorabji 2004, 129). But I think it can be shown that this is a mistake. Aristotle identifies transparency (the fulfillment) with light (418b9-10, 20, 419a11). Although often abused for insisting that light does not move (418b20-6), in fact he is right about this. For the kind of light he has in mind—namely, the kind ‘held to be the contrary of darkness’ (418b18)—is ‘ambient’ light: that is, the kind that is a ‘state’ (ἕξις) of an illuminated environment, as distinct © koninklijke brill nv, leiden, 2018 | doi 10.1163/15685284-12341347 210 Kelsey from the kind propagated in rays from a radiant light-source, e.g. ‘fire or the like’ (418b12). It is true, as Aristotle recognizes, that transparency (the fulfillment) is ultimately produced by such light-sources (cf. 418b11-13, 419a24-5), as the radiant light they propagate into an environment is variously affected by the bodies it meets there (i.e. is variously absorbed, diffracted, refracted and reflected by those bodies) (Bruce and Green 1985, 4-10). But it is also true, as Aristotle also recognizes, that transparency (the fulfillment) is also produced by the colors of bodies—namely, as radiant light is partially reflected by the surfaces of those bodies, in ways that are a function of their location, situation, texture and color. For, Aristotle says, speaking now of radiant light, ‘light is always being reflected’ (τὸ φῶς ἀεὶ ἀνακλᾶται); and the evidence, he continues, speaking now of ambient light, is that ‘otherwise light wouldn’t come to be everywhere, but [there would be] darkness [everywhere] outside what is directly-lit-by-the-sun’ (οὐδὲ γὰρ ἂν ἐγίνετο πάντῃ φῶς, ἀλλὰ σκότος ἔξω τοῦ ἡλιουμένου) (DA 2.8, 419b29-31). Indeed, although Aristotle does not say so, I will hazard the conjecture that, as in fact, so for him, it is in this way alone that colors are ‘kinetic’ (κινητικά) of transparent media: namely, in that they partially reflect (radiant) light—in Aristotle’s language, in that they reflect light, ‘although not in the way it is reflected from water or bronze or even other things that are smooth, viz. in such a way as to cast shadows, which is how we define light’ (419b31-3). In any case, the result is that, for Aristotle, transparent media are only transparent (in fulfillment)—i.e. ‘moveable’ (κινητά) by colors—when and because they are ‘being moved’ (κινούμενα) by those colors. (Note how this parallels the idea that objects of νοῦς are only νοητά [in fulfillment] when and because they are νοούμενα: that is to say, what makes them νοητά is νόησις.) References Bruce, V. and Green, P. (1985), Visual Perception: Physiology, Psychology, and Ecology. London. Johansen, T. K. (1998), Aristotle on the Sense-Organs. Cambridge. Sorabji, R. (2004), ‘Aristotle on Colour, Light and Imperceptibles’, Bulletin of the Institute of Classical Studies 47, 129-40. Phronesis 63 (2018) 209-210