Philo Judaeus Quod Deus Sit Immutabilis 121

[121] On this account it seems to ^{1 2} 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.