“However much beauty might be experienced as the reflection of something supraterrestrial, it is still there in the visible world. That it really is something different, a being of another order, is seen in its mode of appearance. It appears suddenly; and just as suddenly, without any transition, it disappears again. If we must speak with Plato of a hiatus (chorismos) between the world of the senses and the world of ideas, this is where it is and this is where it is also overcome.
“The beautiful appears not only in what is visibly present to the senses, but it does so in such a way that it really exists only through it — i.e., emerges as one out of the whole. The beautiful is of itself truly ‘most radiant’ (to ekphanestaton). The sharp division between the beautiful and what has no share in the beautiful is, moreover, a fact that is well established phenomenologically. Aristotle says of ‘well-formed works’ that nothing can be added to them and nothing taken away. The sensible mean, exactness of proportion, is part of the oldest definition of the beautiful. We need only think of the sensitivity to the tonal harmonies from which music is constructed.
“‘Radiance,’ then, is not only one of the qualities of the beautiful but constitutes its actual being. The distinguishing mark of the beautiful — namely that it immediately attracts the desire of the human soul to it — is founded in its mode of being. The proportionateness of the thing does not simply let it be what it is but also causes it to emerge as a harmonious whole that is proportioned within itself. This is the disclosure (aletheia) of which Plato speaks in the Philebus and which is part of the nature of the beautiful. Beauty is not simply symmetry but appearance itself. It is related to the idea of ‘shining’ (scheinen: also, to appear). ‘To shine’ means to shine on something, and so to make that on which the light falls appear. Beauty has the mode of being of light.
“This means not only that without light nothing beautiful can appear, nothing can be beautiful. It also means that the beauty of a beautiful thing appears in it as light, as a radiance. It makes itself manifest. In fact the universal mode of being of light is to be reflected in itself in this way. Light is not only the brightness of that on which it shines; by making something else visible, it is visible itself, and it is not visible in any other way than by making something else visible. The reflective nature of light was already brought out in classical thought, and correlatively the idea of reflection that plays such an important role in modern philosophy originally belongs to the sphere of optics.
“Obviously it is because of its reflective nature that light combines seeing and the visible, so that without light there can be neither seeing nor anything visible. We recognize the consequences of this trivial observation when we consider the relation of light to the beautiful and the extent of the meaning covered by the beautiful. It is actually light that makes visible things into shapes that are both ‘beautiful’ and ‘good.’ But the beautiful is not limited to the sphere of the visible. It is, as we saw, the mode of appearance of the good in general, of being as it ought to be. The light in which not only the realm of the visible but also that of the intelligible is articulated, is not the light of the sun but the light of the mind, of nous. Plato’s profound analogy already alluded to this; from it Aristotle developed the doctrine of nous and, following him, medieval Christian thought developed that of the intellectus agens. The mind that unfolds from within itself the multiplicity of what is thought is present to itself in what is thought.”
— from Hans-Georg Gadamer, Truth and Method (Second, Revised Edition, Continuum: 2004)