‹‹‹ Vitr. 9.2.3 | Table of Contents | Vitr. 9.3.1 ›››
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.
4On the fourteenth day, being diametrically across the whole extent of the firmament from the sun, she is at her full and rises when the sun is setting. For, as she takes her place over against him and distant the whole extent of the firmament, she thus receives the light from the sun throughout her entire orb. On the seventeenth day, at sunrise, she is inclining to the west. On the twenty-second day, after sunrise, the moon is about mid-heaven; hence, the side exposed to the sun is bright and the rest dark. Continuing thus her daily course, she passes under the rays of the sun on about the twenty-eighth day, and so completes the account of the month.
I will next explain how the sun, passing through a different sign each month, causes the days and hours to increase and diminish in length.