Εἷναι γὰρ πάσης πλάνης καὶ ψενδοδοξίας αἵτιον, τὸ µὴ δύνασθαι διακρίνειν, πῆ τε ἀλλήλοις τἀ ὄντα κοινωνεῖ, καὶ πῆ διενήνοχεν. Εἴ δὲ µὴ κατὰ διωρισµένα τις τὸν λόγον ἐϕοδεύοι, λήσεται συγχέας τά τε κοινὰ καὶ τὰ ἵδια τούτον δὲ γινοµένον, εἰς ἀνοδίαν καὶ πλάνην ἐµπίπτειν αναγκαῖον.

“For the cause of all error and false opinion, is inability to distinguish in what respect things are common, and in what respect they differ. For unless, in things that are distinct, one closely watch speech, he will inadvertently confound what is common and what is peculiar. And where this takes place, he must of necessity fall into pathless tracts and error.”