1. Nox is derived from nocere (to injure) because it injures the eyes. And it has the light of the moon and stars in order that it may not be without beauty, and that it may comfort all who work by night, and that the light may be sufficiently tempered for certain creatures that cannot endure the light of the sun.
3. Night is caused either because the sun is worn out with his long journey and is weary when he comes to the last stretch of heaven and blows out his weakened fires; or because he is driven under the lands with the same force with which he carried his light over them, and thus the shadow of the earth makes night. Whence Virgilius says:
Ruit Oceano nox
Involvens umbra magna terramque polumque.
Chapter 33. On months.
1. The word mensis is Greek, being derived from the word for moon. For in the Greek language the moon is called μήνη; whence among the Hebrews the regular (legitimi) months are reckoned not from the circle of the sun, but from the course of the moon, which is from new moon to new moon.
2. Because of the swifter course of the moon and the fear that an error of reckoning might arise because of its speed, the Egyptians began to reckon the day of the month from the course of the sun, since the slower course of the sun could be comprehended more easily.
Chapter 34. On the solstices and equinoxes.
2. There are two solstices: first, the summer solstice, eight days before the Kalends of July, from which time the sun begins to return to the lower circles; the second, the winter solstice, eight days before the Kalends of January, when the sun begins to make for the higher circles, whence the day of the winter solstice is the shortest and that of the summer solstice the longest.
3. Likewise there are two equinoxes: one in the spring and the other in the autumn, which the Greeks call ἰσημερίαι. These equinoxes are the eighth day before the Kalends of April and the eighth day before the Kalends of October, because the year formerly was divided into two parts only, that is, into the summer and the winter solstice, and into two hemispheres.