Plato, Laws 863c

τρίτον μὴν ἄγνοιαν λέγων ἄν τις τῶν ἁμαρτημάτων αἰτίαν οὐκ ἂν ψεύδοιτο· διχῇ μὴν διελόμενος αὐτὸ ὁ νομοθέτης ἂν βελτίων εἴη, τὸ μὲν ἁπλοῦν αὐτοῦ κούφων ἁμαρτημάτων αἴτιον ἡγούμενος, τὸ δὲ διπλοῦν, ὅταν ἀμαθαίνῃ τις μὴ μόνον ἀγνοίᾳ συνεχόμενος ἀλλὰ καὶ δόξῃ σοφίας, ὡς εἰδὼς παντελῶς περὶ ἃ μηδαμῶς οἶδεν, μετὰ μὲν ἰσχύος καὶ ῥώμης ἑπομένης μεγάλων καὶ ἀμούσων ἁμαρτημάτων τιθεὶς

Nor would it be untrue to say that the third cause of sins is ignorance. This cause, however, the lawgiver would do well to subdivide into two, counting ignorance in its simple form to be the cause of minor sins, and in its double form—where the folly is due to the man being gripped not by ignorance only, but also by a conceit of wisdom, as though he had full knowledge of things he knows nothing at all about,—counting this to be the cause of great and brutal sins when it is joined with strength and might,