[31] And the invisible divine reason, perceptible only by intellect, he calls the image of God. And the image of this image is that light, perceptible only by the intellect, which is the image of the divine reason, which has explained its generation. And it is a star above the heavens, the source of those stars which are perceptible by the external senses, and if any one were to call it universal light he would not be very wrong; since it is from that the sun and the moon, and all the other planets and fixed stars derive their due light, in proportion as each has power given to it; that unmingled and pure light being obscured when it begins to change, according to the change from that which is perceptible only by the intellect, to that which is perceptible by the external senses; for none of those things which are perceptible to the external senses is pure.