V. (14) And the power of this number has extended also to the most useful of the arts–namely, to grammar. At all events, in grammar, the most excellent of the elements, and those which have the most powers, are the seven vowels. And likewise in music, the lyre with seven strings is nearly the best of all instruments; because the euharmonic principle which is the most dignifiedof all the principles of melody, is especially perceived in connection with it. Again, it happens that the tones of the voice are seven–the acute, the grave, the contracted, the aspirate, the lene, the long and the short sound. (15) The number seven is also the first number which is compounded of the perfect number, that is to say of six, and of the unit. And in some sense the numbers which are below ten are either generated by, or do themselves generate those numbers which are below ten, and the number ten itself. But the number seven neither generates any of the numbers below ten, nor is it generated by any of them. On which account the Pythagoreans compare this number to the Goddess always a virgin who was born without a mother, {2}{i.e., Minerva.} because it was not generated by any other, and will not generate any other.

VI. (16) “Accordingly, on the seventh day, God caused to rest from all his works which he had Made.”{3}{#ge 2:2.} Now, the meaning of this sentence is something of this kind. God ceases from forming the races of mortal creatures when he begins to create the divine races, which are akin to the nature of the number seven. And the reference which is here contained to their moral character is of the following nature. When that reason which is holy in accordance with the number seven has entered into the soul the number six is then arrested, and all the mortal things which this number appears to make.