Plato, Epinomis 976d

ἐπιχειροῦμεν, ἑτέραν πάρεξ τῶν εἰρημένων εὑρεῖν, ἣ σοφία μὲν λέγοιτʼ ἂν ὄντως τε καὶ εἰκότως, ὁ δὲ λαβὼν οὔτε βάναυσος οὔτʼ ἠλίθιος ἔσται, σοφὸς δὲ καὶ ἀγαθὸς διʼ αὐτὴν πολίτης τε καὶ ἄρχων καὶ ἀρχόμενος ἐνδίκως ἔσται πόλεως ἅμα καὶ ἐμμελής. κατίδωμεν δὴ ταύτην πρώτην, τίς ποτʼ ἐκ τῆς ἀνθρωπίνης φύσεως ἐπιστήμη μία διεξελθοῦσα ἢ μὴ παραγενομένη τῶν νῦν παρουσῶν ἀνοητότατον ἂν καὶ ἀφρονέστατον παράσχοιτο ζῷον τὸ τῶν ἀνθρώπων. οὐ δὴ

apart from those we have mentioned, which can really and reasonably be termed wisdom; such an acquirement as will not make one a mean and witless drudge, but will enable one to be a wise and good citizen, at once a just ruler and subject of his city, and decorous. So let us examine this one first, and see what single science it is of those that we now have which, by removing itself or being absent from human nature, must render mankind the most thoughtless and senseless of creatures.