17. The course of the Moon through the signs
THE RECKONING OF TIME
can be said about this, but it can be done to better e¡ect by someone speaking than through the written word.
Because we discussed above177 the order and periodicity [tempore] of the planets which course through the zodiac, we will merely repeat here that the Sun illumines the circuit of the zodiac in 365 days and 6 hours, the Moon in 27 days and 8 hours. The Sun slips through each of the signs in 30 days and 10ˆ~˜ hours, the Moon in 2 days and 6˜~¯ [bisse] hours. Should you ask what bisse means, I shall now repeat brie£y what I stated in the beginning of this little work about measures.178 A bisse is smaller than a whole hour in the same proportion as 8 is smaller than 12, 20 than 30, 10 than 15. Take away a third part, and two parts remain every time; these two parts are called the bisse, and the third is called triens. Therefore they are mistaken who say that the Moon traverses as much of the heavens in thirty days as the Sun does in 365 days, since (as we stipulated earlier) the plain truth demonstrates that the Moon is held to complete as much of the course in 27ˆ~¯ days as the Sun completes in 365ˆ~˘ /337/ days, and that the Moon covers as much territory in one of its [synodic] months as the orbit of the Sun does in 13 of its months.179
17. THE COURSE OF THE MOON THROUGH THE SIGNS
Every day the Moon either retreats from the Sun by four puncti with respect to [its location on] the preceding day when it is waxing, or approaches the Sun by four puncti, when waning.180 As we observed
177 Ch. 8.
178 Ch. 4.
179 It is Isidore who is in error: DNR 19.1 (247.5^8), and Etym. 5.36.3. But so also is Ambrose, Hexaemeron 4.5.24 (131.17^21); cf. ch.18 below.The Moon returns to the point in the zodiac where it was new in 27ˆ~¯ days, but must ''catch up'' with the Sun, which has meanwhile moved into the next zodiac sign, before conjunction can take place. Hence, as Bede puts it, the zodiacal distance covered by a synodic month is the equivalent of 13 solar months.
180 As Bede explained above, the Moon circles the zodiac at a much faster rate than does the Sun. At conjunction, Moon and Sun will occupy the same point on the zodiac, but with each day it waxes, the Moon will pull ahead of the Sun at the rate of about ˜~˙ of a zodiac sign per day, until it is full ^ or in other words,until it is exactly opposite the Sun on the zodiacal band. Then, as it wanes, it continues along the zodiac, but now returning towards the Sun, again at the rate of about ˜~˙ of a sign per day.
TRANSLATION
above,181 every sign has ten ''puncti'', that is, two hours,182 for ¢ve ''puncti'' make one hour.183 So if you want to know what sign the Moon is in, take whatever [day of the] Moon /338/ you wish ^ the ¢fth, for example. Multiply it by 4,184 which makes 20. Divide by 10185 (10 times
2 is 20); therefore the ¢fth Moon is separated from the Sun by two signs.
Then again, take the eighth [day of the] Moon. Multiply by 4 and that makes 32. Divide by 10. 3 times 10 yields 30, with 2 remaining. Therefore the eighth Moon is separated from the Sun by three signs and two puncti. You know that two puncti equal six partes, that is, the distance covered by the Sun in its journey through the zodiac in six days. A punctus has three partes, so each sign has 10 puncti or 30 partes. Once again, take the nineteenth Moon. Multiply by 4, which makes 76.
Divide by 10: 7 times 10 yields 70 with 6 remaining. Therefore, on the journey which it began away from the Sun, the Moon has parted company with it by seven signs, plus one hour, which is half a sign and a punctus, that is, three partes. And lest you suspect a faulty argument,
¢nd the point which no one can doubt is diametrically opposite [the position of] the ¢fteenth Moon. Multiply 15 by four, which makes 60. Divide by 10: 60 divided by 10 is 6. Now the ¢fteenth Moon can always be seen six signs away from the Sun, that is, half of the celestial sphere away, whether you look ahead or behind.
Therefore you see the orb of the Moon to be completely full whenever it is opposite the Sun; /339/ you see it low [in the sky] when the Sun is high, and high when it is low.186 For to be sure, when the Sun is in the summer circle [i.e. tropic of Cancer], the Moon, when it is full, is in the winter circle; when it is full and the Sun has dipped down into the winter
181 Ch. 3.
182 ''every sign . . . hours'': De causis quibus nomina acceperunt duodecim signa,
667.64^65. What Bede means is that each sign represents 1 12 of the daily revolution of the heavenly sphere about the Earth, or in other words, 2 hours.
183 De causis quibus nomina acceperunt duodecim signa 667.64^65. Note that Bede is speaking of ''lunar puncti'' here; ordinarily, an hour has four puncti, as he points out in ch. 3.
184 I.e. the number of puncti by which the Moon advances towards or retreats from the Sun each day.
185 I.e. the number of puncti in a zodiac sign.
186 ''Therefore you see the orb . . . when it is low.'' Cf. ch. 6. What Bede means is that when the Sun is farthest to the north (i.e. ''high'' in the sky, or closest to zenith) at the summer solstice in Cancer, the Moon at full will be in Capricorn, ''low'' in the sky to the south, and vice versa. See ch. 26 and Commentary.