על בריאת העולם ל׳On the Account of the World's Creation 30
א׳
1[89] Now when the whole world had been brought to completion in accordance with the properties of six, a perfect number, the Father invested with dignity the seventh day which comes next, extolling it and pronouncing it holy; for it is the festival, not of a single city or country, but of the universe, and it alone strictly deserves to be called “public” as belonging to all people and the birthday of the world.
ב׳
2[90] I doubt whether anyone could adequately celebrate the properties of the number 7, for they are beyond all words. Yet the fact that it is more wondrous than all that is said about it is no reason for maintaining silence regarding it. Nay, we must make a brave attempt to bring out at least all that is within the compass of our understandings, even if it be impossible to bring out all or even the most essential points. Now, 7 or 7th is a term used in two different senses. There is the 7 inside the number 10. This consists of 7 units, and is determined by the sevenfold repetition of the unit. There is the 7 outside the number 10.
ג׳
3[91] This is a number starting throughout from the number 1 and formed by doubling it and going on doubling (7 times) or trebling, or multiplying by any other number in regular progression; as, for example, the number 64 is the product of doubling from 1 onwards, and the number 729 that of trebling. Each of these forms claims more than casual notice. The second form, clearly has a very manifest superiority.
ד׳
4[92] For invariably the 7th term of any regular progression, starting from unity and with a ratio of 2, 3, or any other number, is both a cube and a square, embracing both forms, that of the incorporeal and that of the corporeal substance, the form of the incorporeal answering to the surface which is formed by squares, that of the corporeal answering to the solid which is formed by cubes.
ה׳
5[93] The plainest evidence of this are the numbers already mentioned: for instance, the 7th from 1 reached by going on doubling, i.e. 64, is a square, being 8 times 8, and a cube, being 4 times 4, again multiplied by 4: and again the 7th from 1 reached by progressive trebling, 729, is a square, being the product of 27 multiplied by itself, and the cube of 9, i.e. 9 times 9, again multiplied by 9.
ו׳
6[94] And invariably if one takes the 7th number for his starting-point instead of the unit, and multiplies in corresponding fashion up to a (fresh) 7th, he is sure to find the product both a cube and a square: for instance starting from 64 the number formed by continuous doubling will give us seventh 4096. This is at once a square and a cube—a square with 64 as its side and a cube with 16.