From, Iamblichus: The Life of Pythagoras. Ch. 33. Translated by Kenneth S. Guthrie.
Friendship of all things towards all was most clearly unfolded
by Pythagoras. Indeed, the friendship of Gods towards men he explained through
piety and scientific cultivation; but that of teachings towards each other, and
generally of the soul to the body, of the rational towards the irrational part
he unfolded, through philosophy and its teaching. That of men towards each
other, and of citizens, he justified through proper legislation; that of
strangers, through the common possession of a body; that between man and wife,
children, brothers or kindred, through the unperverted ties of nature. In short,
he taught the friendship of all for all; and still further, of certain animals,
through justice, and common physical experiences. But the pacification and
conciliation of the body, which is mortal by itself, and of its latent immortal
powers, he enforced through health, and temperate diet suitable thereto, in
imitation of the ever-healthy condition of the mundane elements.