Plato, Meno 84b

ἀπορεῖν ἤδη, καὶ ὥσπερ οὐκ οἶδεν, οὐδʼ οἴεται εἰδέναι. ἀληθῆ λέγεις. οὐκοῦν νῦν βέλτιον ἔχει περὶ τὸ πρᾶγμα ὃ οὐκ ᾔδει; καὶ τοῦτό μοι δοκεῖ. ἀπορεῖν οὖν αὐτὸν ποιήσαντες καὶ ναρκᾶν ὥσπερ ἡ νάρκη, μῶν τι ἐβλάψαμεν; οὐκ ἔμοιγε δοκεῖ. προὔργου γοῦν τι πεποιήκαμεν, ὡς ἔοικε, πρὸς τὸ ἐξευρεῖν ὅπῃ ἔχει· νῦν μὲν γὰρ καὶ ζητήσειεν ἂν ἡδέως οὐκ εἰδώς, τότε δὲ ῥᾳδίως ἂν καὶ πρὸς πολλοὺς καὶ πολλάκις

he knows. That is true. And is he not better off in respect of the matter which he did not know? I think that too is so. Now, by causing him to doubt and giving him the torpedo’s shock, have we done him any harm? I think not. And we have certainly given him some assistance, it would seem, towards finding out the truth of the matter: for now he will push on in the search gladly, as lacking knowledge; whereas then he would have been only too ready to suppose he was right in saying, before any number of people any number of times,