Plato, Republic, book 1 340:

οὐ καὶ ἡ τέχνη, ἦν δ’ ἐγώ, ἐπὶ τούτῳ πέφυκεν, ἐπὶ τῷ τὸ συμφέρον ἑκάστῳ ζητεῖν τε καὶ ἐκπορίζειν;