Chapter VI.
The magnitude of the sun and moon is proven by the fact that they appear the same to everyone. The objection is resolved and a beautiful discussion about the appearance of distant objects follows: once the magnitude of the sun has been asserted, some remarks are added about its temperament.
25. Therefore God made these two great lights. We can understand them to be great not only in comparison to other things, but also by their own function, as the great sky and the great ocean. For the great sun, which fills the earth with its heat, and the moon with its light, not only illuminate the lands, but also this air and sea, and the face of the sky. Wherever they are in the sky, they illuminate everything and are seen equally by all; so that no people believe that these lights reside only in their own regions, and only exist and shine for themselves; since they shine in the same way for all, so that no one thinks that one light is closer to them than another. An example of their size is evident, as the same appearance of the moon is seen by all people on Earth. For although its light may sometimes increase or decrease, it appears the same to me and to everyone else during the night; for if it appeared smaller to those who are far away, it would shine brighter to those who are closer, and it would reveal an indication of its narrowness and smallness. Indeed, we consider other objects that are far away to be smaller, and we believe them to be larger when we observe them up close; the closer you are, the more the size of what you perceive is magnified. The radius of the sun is closer to none and farther from none; similarly, the globe of the moon is equal to all. The sun appears the same to both the Indians and the Britons at the same moment when it rises. Neither when it sets, does it appear smaller to the Easterners than to the Westerners; nor, when it rises to the Westerners, is it considered lower than to the Easterners. How far, he asks, is the East from the West (Ps. CII, 12)? These things are distant from each other in turn. But the sun is distant from none, closer to none, and farther from none.
26. And let it not bother you that, when it rises, the sun appears to you as the size of a fist: but consider how much space there is between the sun and the earth, which our weak vision cannot pass without great loss to itself. Our vision becomes dim, does the sun become dim, or the moon? Our sight is limited, does that make the things we see smaller? The appearance is diminished, not the size taken away. For we should not attribute the weaknesses of our vision to the luminaries themselves. Our appearance deceives: therefore do not estimate the judgment of it as faithful. The form of the heavenly bodies is smaller than the spectacle, not its own. If you desire to see a plain subject from the highest peak of mountains, and there grazing herds, will you not judge their bodies as resembling ants? If you look at the sea from some lookout of the shore, will not the largest ships among the blue waves, and the shining sails appear as if they cover the appearance of flying doves from a distance? What about those very islands that divide the sea, separate the lands, which are considered to be enclosed by a narrow boundary? How do they appear round from rough things, thick from sparse ones? So consider these weaknesses of your sight; and call upon yourself, as a just judge, the evidence of what we assert.
27. If you want to estimate the magnitude of the sun, not only with the eye of the mind, but also with the body, consider how many spheres of stars seem to be woven into the axis of the sky and adorned with countless lights; yet they cannot dispel the darkness of night or clear the clouds of the sky. As soon as the sun has sent forth its signs of its rising, all the fires of the stars vanish under the brilliance of the one luminary, the air opens up, and the face of the sky is suffused with a reddish purple blush. While still breathing its beginning, and now with the momentary swiftness of full light, the gleaming spark moves, and the sweet breeze precedes the rising sun. Tell me, please, if the world were not vast, how could it illuminate the great sphere of the earth?
28. But what can I say about the such great restraint and moderation of the creator, who assigned to it the measure of the sun's function; so that neither its fiery vapor, as it seems, would consume the veins of the earth, its juices, and the forms of things infused, nor, cooled again over such vast spaces of the world, would it endure any seed of heat in the earth, but leaving it barren and needy of fruits, it might not pour forth any grace of fertility?