The Ten Books on Architecture, 9.2.2

Vitruvius  Parallel editions

‹‹‹ Vitr. 9.2.1 | Table of Contents | Vitr. 9.2.3 ›››

Gwilt translation

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.

Morgan translation

2As 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.