Plato, Laws 875a

ἢ μηδὲν διαφέρειν τῶν πάντῃ ἀγριωτάτων θηρίων. ἡ δὲ αἰτία τούτων ἥδε, ὅτι φύσις ἀνθρώπων οὐδενὸς ἱκανὴ φύεται ὥστε γνῶναί τε τὰ συμφέροντα ἀνθρώποις εἰς πολιτείαν καὶ γνοῦσα, τὸ βέλτιστον ἀεὶ δύνασθαί τε καὶ ἐθέλειν πράττειν. γνῶναι μὲν γὰρ πρῶτον χαλεπὸν ὅτι πολιτικῇ καὶ ἀληθεῖ τέχνῃ οὐ τὸ ἴδιον ἀλλὰ τὸ κοινὸν ἀνάγκη μέλειν—τὸ μὲν γὰρ κοινὸν συνδεῖ, τὸ δὲ ἴδιον διασπᾷ τὰς πόλεις—καὶ ὅτι συμφέρει τῷ κοινῷ τε καὶ ἰδίῳ, τοῖν ἀμφοῖν, ἢν τὸ κοινὸν

the most savage of beasts. The reason thereof is this,—that no man’s nature is naturally able both to perceive what is of benefit to the civic life of men and, perceiving it, to be alike able and willing to practice what is best. For, in the first place, it is difficult to perceive that a true civic art necessarily cares for the public, not the private, interest,—for the public interest bind States together, whereas the private interest rends them asunder,—and to perceive also that it benefits both public and private interests alike when the public interest, rather than the private, is well enacted.