2Berosus, who travelled into Asia from the state or country of the Chaldeans, teaching his doctrines, maintained that the moon was a ball, half whereof was luminous, and the remaining half of a blue colour; and that when, in its course, it approached the sun; attracted by the rays and the force of the heat, it turned its bright side in that direction, from the sympathy existing between light and light; whence, when the sun is above it, the lower part, which is not luminous, is not visible, from the similarity of its colour to the air. When thus perpendicular to the sun’s rays, all the light is confined to its upper surface, and it is then called the new moon.
2When it passes towards the east, the sun begins to have less effect upon it, and a thin line on the edge of its bright side emits its splendour towards the earth. This is on the second day: and thus, from day to day, advancing in its circuit, the third and fourth days are numbered: but, on the seventh day, when the sun is in the west, the moon is in the middle, between the east and the west; and being distant from the sun half the space of the heavens, the luminous half side will be towards the earth. Lastly; when the sun and the moon are the whole distance of the heavens from each other, and the former, passing towards the west, shines full on the moon behind it in the east, being the fourteenth day, it is then at the greatest distance from its rays, and the complete circle of the whole orb emits its light. In the remaining days it gradually decreases till the completion of the lunar month, and then returns to re-pass under the sun; its monthly rays being determined by the number of days.
3I shall now subjoin what Aristarchus, the Samian mathematician, learnedly wrote on this subject, though of a different nature. He asserted, that the moon possesses no light of its own, but is similar to a speculum, which receives its splendour from the sun’s rays. Of the planets, the moon makes the smallest circuit, and is nearest to the earth; whence, on the first day of its monthly course, hiding itself under the sun, it is invisible; and when thus in conjunction with the sun, it is called the new moon. The following day, which is called the second, removing a little from the sun, it receives a small portion of light on its disc. When it is three days distant from him, it has increased, and become more illuminated; thus daily elongating from him, on the seventh day, being half the heavens distant from the western sun, one half of it shines, namely, that half which is lighted by the sun.
4On the fourteenth day, being diametrically opposite to the sun, and the whole of the heavens distant from him, it becomes full, and rises as the sun sets; and its distance being the whole extent of the heavens, it is exactly opposite to, and its whole orb receives, the light of the sun. On the seventeenth day, when the sun rises, it inclines towards the west; on the twenty-first day, when the sun rises, the moon is about mid-heaven, and the side next the sun is enlightened, whilst the other is in shadow. Thus advancing every day, about the twenty-eighth day it again returns under the rays of the sun, and completes its monthly rotation. I will now explain how the sun, in his passage through a sign every month, causes the days and hours to increase and diminish.