Plato, Meno 76d

πόρων, τὰς δὲ ἐλάττους ἢ μείζους εἶναι; ἔστι ταῦτα. οὐκοῦν καὶ ὄψιν καλεῖς τι; ἔγωγε. ἐκ τούτων δὴ σύνες ὅ τοι λέγω, ἔφη Πίνδαρος. ἔστιν γὰρ χρόα ἀπορροὴ σχημάτων ὄψει σύμμετρος καὶ αἰσθητός. ἄριστά μοι δοκεῖς, ὦ Σώκρατες, ταύτην τὴν ἀπόκρισιν εἰρηκέναι. ἴσως γάρ σοι κατὰ συνήθειαν εἴρηται· καὶ ἅμα οἶμαι ἐννοεῖς ὅτι ἔχοις ἂν ἐξ αὐτῆς εἰπεῖν καὶ φωνὴν ὃ ἔστι,

while some are too small or too large? That is so. And further, there is what you call sight? Yes. So now conceive my meaning, as Pindar says: color is an effluence of figures, commensurate with sight and sensible. Your answer, Socrates, seems to me excellently put. Yes, for I expect you find its terms familiar; and at the same time I fancy you observe that it enables you to tell what sound and smell are, and numerous other