1. The sun, being made of fire, heats to a whiter glow because of the excessive speed of its circular motion. And its fire, philosophers declare, is fed with water, and it receives the virtue of light and heat from an element opposed to it. Whence we see that it is often wet and dewy.
Chapter 50. On the motion of the sun.
1. They say that the sun has a motion of its own and does not turn with the universe. For if it remained fixed in the heavens all days and nights would be equal, but since we see that it will set to-morrow in a different place from where it set yesterday, it is plain that it has a motion of its own and does not move with the universe. For it accomplishes its yearly orbits by varying courses, on account of the changes of the seasons.
2. For going further to the south it makes winter, in order that the land may be enriched by winter rains and frosts. Approaching the north it restores the summer, in order that fruits may mature, and what is green in the damp weather may ripen in the heat.
Chapter 51. What the sun does.
1. The rising sun brings the day, the setting sun the night; for day is the sun above the earth, night is the sun beneath the earth. From the sun come the hours; from the sun, when it rises, the day; from the sun, too, when it sets, the night; from the sun the months and years are numbered; from the sun come the changes of the seasons.
2. When it runs through the south it is nearer the earth; when it passes toward the north it is raised aloft. God has appointed for it different courses, places, and times for this reason, lest if it always remained in the same place all things should be consumed by its daily heat—just as Clement says: “It takes on different motions, by which the temperature of the air is moderated with a view to the seasons, and a regular order is observed in its seasonal changes and permutations. For when it ascends to the higher parts it tempers the spring, and when it comes to the summit of heaven it kindles the summer heats; descending again, it gives autumn its temperature. And when it returns to the lower circle it leaves to us the rigor of winter cold from the icy quarter of the heavens.”
Chapter 52. On the journey of the sun.
1. The eastern sun holds its way through the south, and after it comes to the west and has bathed itself in ocean, it passes by unknown ways beneath the earth, and again returns to the east.
Chapter 53. On the light of the moon.