Aristotle, Metaphysics, Book 12 122:

φαίνεται δ’ ἀεὶ ἄλλου ἡ ἐπιστήμη καὶ ἡ αἴσθησισ καὶ ἡ δόξα καὶ ἡ διάνοια, αὑτῆσ δ’ ἐν παρέργῳ. ἔτι εἰ ἄλλο τὸ νοεῖν καὶ τὸ νοεῖσθαι, κατὰ πότερον αὐτῷ τὸ εὖ ὑπάρχει; οὐδὲ γὰρ ταὐτὸ τὸ εἶναι νοήσει καὶ νοουμένῳ. ἢ ἐπ’ ἐνίων ἡ ἐπιστήμη τὸ πρᾶγμα, ἐπὶ μὲν τῶν ποιητικῶν ἄνευ ὕλησ ἡ οὐσία καὶ τὸ τί ἦν εἶναι, ἐπὶ δὲ τῶν θεωρητικῶν ὁ λόγοσ τὸ πρᾶγμα καὶ ἡ νόησισ;