XXV. (116) Reject therefore with all your might all idea of pleasing the keepers of the prison; but on the contrary, with all your ability and all your earnestness, labour to please him who is the cause of all things; and if you are unable to do so, (for the greatness of his dignity is exceeding high), at all events advance, without ever turning back, towards his powers, and present yourself to them as their suppliant, until they admitting the continual assiduity and sincerity of your service, place you in the ranks of those who have pleased them, as they did Noah, of whose descendants Moses has made a most admirable and novel catalogue; (117) for he says, "These are the generations of Noah: Noah was a just man, being perfect in his generation, and Noah pleased God;"29 for the descendants of the compound being were naturally compound beings also themselves; for horses do of necessity beget horses, and lions beget lions, bulls become the parents of bulls, and so too men beget men; (118) but such things are not the appropriate offspring of a good mind; the progeny of that are the virtues before mentioned, namely the being a man, the being just, the being perfect, the pleasing God, which last particular, inasmuch as it is the crowning one, and as it were the boundary of perfect happiness, is enumerated last of all. (119) But there is one kind of creation, which is a sort of conducting and travelling from that which does not exist to existence. This is the one which plants, and animals do of necessity use; and there is another kind, which is a transition and change from a better genus to a rose species, which Moses mentions when he says, "These are the generations of Jacob; Joseph when he was seventeen years of age, was keeping the sheep with his brethren, being a youth with the sons of Billah, and with the sons of Zilpah, his father's wives."30 (120) For when this reason inclined to meditation and devoted to learning, was driven down from its more divine speculations, human and mortal opinions, then Joseph, the companion of the body, and of all the things which pertain to the body was born, being still but a youth, even though in the lapse of time he may become greyheaded, as being one who never listened to any older discourse or opinions, which the companions of Moses acquired as the most useful possessions for themselves and their disciples. (121) On this account it seems to me that Moses wishing to describe his figure and to give a more accurate idea of his appearance, so as to make it known, introduced him as tending his father's sheep, not in the company of any one of his father's legitimate sons, but with his illegitimate brethren, who, being the sons of concubines, derive their name from the inferior sex, that of the women, and not from the superior sex, that, namely of the man; for they here are called the sons of Jacob's wives, Billah and Zilpah, and not the sons of their father Israel.