Genesis 1:15

15. Let them be for lights It is well again to repeat what I have said before, that it is not here philosophically discussed, how great the sun is in the heaven, and how great, or how little, is the moon; but how much light comes to us from them. For Moses here addresses himself to our senses, that the knowledge of the gifts of God which we enjoy may not glide away. Therefore, in order to apprehend the meaning of Moses, it is to no purpose to soar above the heavens; let us only open our eyes to behold this light which God enkindles for us in the earth. By this method (as I have before observed) the dishonesty of those men is sufficiently rebuked, who censure Moses for not speaking with greater exactness. For as it became a theologian, he had respect to us rather than to the stars. Nor, in truth, was he ignorant of the fact, that the moon had not sufficient brightness to enlighten the earth, unless it borrowed from the sun; but he deemed it enough to declare what we all may plainly perceive, that the moon is a dispenser of light to us. That it is, as the astronomers assert, an opaque body, I allow to be true, while I deny it to be a dark body. For, first, since it is placed above the element of fire, it must of necessity be a fiery body. Hence it follows, that it is also luminous; but seeing that it has not light sufficient to penetrate to us, it borrows what is wanting from the sun. He calls it a lesser light by comparison; because the portion of light which it emits to us is small compared with the infinite splendor of the sun.