Parmenides, R44 = Generation and Corruption Arist. GC 1.8 325a2–23
“So, then, for these reasons, too, people make claims about the truth. And even if it seems to be the case that these assertions are correct about arguments, it is nearly close to madness to think the same way when it comes to facts.
For no crazy person is so twisted as to believe that fire and ice are the same thing! No, beautiful things and those which seem beautiful only appear not to be different at all to some people because of habit, because of madness.”
οἱ μὲν οὖν οὕτως καὶ διὰ ταύτας τὰς αἰτίας ἀπεφήναντο περὶ τῆς ἀληθείας· ἐπεὶ δὲ ἐπὶ τῶν λόγων μὲν δοκεῖ ταῦτα συμβαίνειν, ἐπὶ δὲ τῶν πραγμάτων μανίᾳ παραπλήσιον εἶναι τὸ δοξάζειν οὕτως· οὐδένα γὰρ τῶν μαινομένων ἐξεστάναι τοσοῦτον ὥστε τὸ πῦρ ἓν εἶναι δοκεῖν καὶ τὸν κρύσταλλον, ἀλλὰ μόνον τὰ καλὰ καὶ τὰ φαινόμενα διὰ συνήθειαν, ταῦτ’ ἐνίοις διὰ τὴν μανίαν οὐθὲν δοκεῖ διαφέρειν.