Plato, Republic, book 10 187:

καὶ ταὐτὰ καμπύλα τε καὶ εὐθέα ἐν ὕδατί τε θεωμένοισ καὶ ἔξω, καὶ κοῖλά τε δὴ καὶ ἐξέχοντα διὰ τὴν περὶ τὰ χρώματα αὖ πλάνην τῆσ ὄψεωσ, καὶ πᾶσά τισ ταραχὴ δήλη ἡμῖν ἐνοῦσα αὕτη ἐν τῇ ψυχῇ·