Plato, Meno 88b

τοιαῦτα; ἔγωγε. σκόπει δή, τούτων ἅττα σοι δοκεῖ μὴ ἐπιστήμη εἶναι ἀλλʼ ἄλλο ἐπιστήμης, εἰ οὐχὶ τοτὲ μὲν βλάπτει, τοτὲ δὲ ὠφελεῖ; οἷον ἀνδρεία, εἰ μὴ ἔστι φρόνησις ἡ ἀνδρεία ἀλλʼ οἷον θάρρος τι· οὐχ ὅταν μὲν ἄνευ νοῦ θαρρῇ ἄνθρωπος, βλάπτεται, ὅταν δὲ σὺν νῷ, ὠφελεῖται; ναί. οὐκοῦν καὶ σωφροσύνη ὡσαύτως καὶ εὐμαθία· μετὰ μὲν νοῦ καὶ μανθανόμενα καὶ καταρτυόμενα ὠφέλιμα, ἄνευ δὲ νοῦ βλαβερά; πάνυ

Yes. Now tell me; such of these as you think are not knowledge, but different from knowledge—do they not sometimes harm us, and sometimes profit us? For example, courage, if it is courage apart from prudence, and only a sort of boldness: when a man is bold without sense, he is harmed; but when he has sense at the same time, he is profited, is he not? Yes. And the same holds of temperance and intelligence: things learnt and coordinated with the aid of sense are profitable, but without sense they are harmful?