e moon is a ball, one half luminous and the rest of a blue
colour. When, in the course of her orbit, she has passed below the disc
of the sun, she is attracted by his rays and great heat, and turns
thither her luminous side, on account of the sympathy between light and
light. Being thus summoned by the sun's disc and facing upward, her
lower half, as it is not luminous, is invisible on account of its
likeness to the air. When she is perpendicular to the sun's rays, all
her light is confined to her upper surface, and she is then called the
new moon.

2. As she moves on, passing by to the east, the effect of the sun upon
her relaxes, and the outer edge of the luminous side sheds its light
upon the earth in an exceedingly thin line. This is called the second
day of the moon. Day by day she is further relieved and turns, and thus
are numbered the third, fourth, and following days. On the seventh day,
the sun being in the west and the moon in the middle of the firmament
between the east and west, she is half the extent of the firmament
distant from the sun, and therefore half of the luminous side is turned
toward the earth. But when the sun and moon are separated by the entire
extent of the firmament, and the moon is in the east with the sun over
against her in the west, she is completely relieved by her still greater
distance from his rays, and so, on the fourteenth day, she is at the
full, and her entire disc emits its light. On the succeeding days, up to
the end of the month, she wanes daily as she turns in her course, being
recalled by the sun until she comes under his disc and rays, thus
completing the count of the days of the month.

3. But Aristarchus of Samos, a mathematician of great powers, has left a
different explanation in his teaching on this subject, as I shall now
set forth. It is no secret that the moon has no light of her own, but
is, as it were, a mirror, receiving brightness from the influence of the
sun. Of all the seven stars, the moon traverses the shortest orbit, and
her course is nearest to the earth. Hence in every month, on the day
before she gets past the sun, she is under his disc and rays, and is
consequently hidden and invisible. When she is thus in conjunction with
the sun, she is called the new moon. On the next day, reckoned as her
second, she gets past the sun and shows the thin edge of her sphere.
Three days away from the sun, she waxes and grows brighter. Removing
further every day till