In order that both these things may be the better understood, let us make a comparison. A ray of sunlight is striking a window. If the window is in any way stained or misty, the sun’s ray will be unable to illumine it and transform it into its own light, totally, as it would if it were clean of all these things, and pure; but it will illumine it to a lesser degree, in proportion as it is less free from those mists and stains; and will do so to a greater degree, in proportion as it is cleaner from them, and this will not be because of the sun’s ray, but because of itself; so much so that, if it be wholly pure and clean, the ray of sunlight will transform it and illumine it in such wise that it will itself seem to be a ray and will give the same light as the ray. Although in reality the window has a nature distinct from that of the ray itself, however much it may resemble it, yet we may say that that window is a ray of the sun or is light by participation. And the soul is like this window, whereupon is ever beating (or, to express it better, wherein is ever dwelling) this Divine light of the Being of God according to nature, which we have described.