On Sobriety (65)

And what is said in the scriptures appears to coincide with this, for Shem is planted as a root of excellence and virtue; and from this root there sprang up a tree bringing forth good fruit, namely, Abraham, of whom the self-instructed and self-teaching offspring, Isaac, was the fruit, by whom again the virtues which are displayed in labour are sown, the practiser of which is Jacob, the man trained and exercised in wrestling with the passions, having the admonitions of angels for his gymnastic trainers.