Thucydides 5.89

ἐπισταμένους πρὸς εἰδότας ὅτι δίκαια μὲν ἐν τῷ ἀνθρωπείῳ λόγῳ ἀπὸ τῆς ἴσης ἀνάγκης κρίνεται, δυνατὰ δὲ οἱ προύχοντες πράσσουσι καὶ οἱ ἀσθενεῖς ξυγχωροῦσιν.

You know as well as we do that justice, as a matter of human reckoning, is something to be decided between equals, while those who are more powerful do what they are capable of doing, and the weak accept what they have to accept.