Philonis Judaei Opera Omnia (Vol. 7)

Why does he say: In the fourth generation they will return here? Genesis 15:16

§. 12. The number four is more suitable than all numbers as it is more perfect, and it is the root and foundation of the most perfect decade. And according to the ratio of the fourth, all things gathered return here, as he himself said: Just as it is perfect in itself, it also generates things that are perfectly complete. What is it, however, that I am saying? In the generation of living beings, the first place is held by sowing; the second, by the imprinting of individual instruments through something neighboring to nature; the third, by growth after the formation; the fourth, finally, above all, is perfection and birth. The same ratio holds for plants: the seed is sent into the earth, then it is promoted upward and downward, partly into roots, partly into branches; after this it grew and in the fourth stage it produced fruit. Likewise, trees, having been formed, first produce fruit, which subsequently grows; third, it changes color while ripening; and fourth, which is the final stage, it fills and perfects the work, the consequence of which is its use and fruit.