Learn from enemies

The wise learn many things from their enemies.

Ἀλλ´ ἀπ´ ἐχθρῶν δῆτα πολλὰ μανθάνουσιν οἱ σοφοί.

Aristophanes – Greek comic playwright (455-385 B.C.), from “The Birds”, l. 375 (“Ὄρνιθες”, 414 B.C.)