It should be understood that the moon was made full by the Creator, that is, a fifteen days’ moon: for it was fitting that it should be made complete Sever. Gabal., De opif. mundi, III.. But on the fourth day, as we said, the sun was created. Therefore the moon was eleven days in advance of the sun, because from the fourth to the fifteenth day there are eleven days. Hence it happens that in each year the twelve months of the moon contain eleven days fewer than the twelve months of the sun. For the twelve months of the sun contain three hundred and sixty-five and a quarter days, and so because the quarter becomes a whole, in four years an extra day is completed, which is called bis-sextile. And that year has three hundred and sixty-six days. The years of the moon, on the other hand, have three hundred and fifty-four days. For the moon wanes from the time of its origin, or renewal, till it is fourteen and three-quarter days’ old, and proceeds to wane till the twenty-ninth and a half day, when it is completely void of light. And then when it is once more connected with the sun it is reproduced and renewed, a memorial of our resurrection. Thus in each year the moon gives away eleven days to the sun, and so in three years the intercalary month of the Hebrews arises, and that year comes to consist of thirteen months, owing to the addition of these eleven days Ibid. De opif. mundi, III..