Ἆρ’ οὖν σοι δοκεῖ ἔτι τοῦδε προσδεῖσθαι ὁ φυλακικὸς ἐσόμενος, πρὸς τῷ θυμοειδεῖ ἔτι προσγενέσθαι φιλόσοφος τὴν φύσιν; – Πῶς δή; ἔφη· οὐ γὰρ ἐννοῶ. – Καὶ τοῦτο, ἦν δ’ ἐγώ, ἐν τοῖς κυσὶ κατόψει, ὃ καὶ ἄξιον θαυμάσαι τοῦ θηρίου. – Τὸ ποῖον; – Ὃν μὲν ἂν ἴδῃ ἀγνῶτα, χαλεπαίνει, οὐδὲν δὲ κακὸν προπεπονθώς· ὃν δ’ ἂν γνώριμον, ἀσπάζεται, κἂν μηδὲν πώποτε ὑπ’ αὐτοῦ ἀγαθὸν πεπόνθῃ. ἢ οὔπω τοῦτο ἐθαύμασας; – Οὐ πάνυ, ἔφη, μέχρι τούτου προσέσχον τὸν νοῦν· ὅτι δέ που δρᾷ ταῦτα, δῆλον. – Ἀλλὰ μὴν κομψόν γε φαίνεται τὸ πάθος αὐτοῦ τῆς φύσεως καὶ ὡς ἀληθῶς φιλόσοφον. – Πῇ δή; – Ἧι, ἦν δ’ ἐγώ, ὄψιν οὐδενὶ ἄλλῳ φίλην καὶ ἐχθρὰν διακρίνει, ἢ τῷ τὴν μὲν καταμαθεῖν, τὴν δὲ ἀγνοῆσαι· καίτοι πῶς οὐκ ἂν φιλομαθὲς εἴη, συνέσει τε καὶ ἀγνοίᾳ ὁριζόμενον τό τε οἰκεῖον καὶ τὸ ἀλλότριον; – Οὐδαμῶς, ἦ δ’ ὅς, ὅπως οὔ.
(Plato, Politeia 375e-376b)
‘Would not he who is fitted to be a guardian, besides the spirited nature, need to have the qualities of a philosopher?’ – ‘I do not apprehend your meaning.’ – ‘The trait of which I am speaking,’ I replied, ‘may be also seen in the dog, and is remarkable in the animal.’ – ‘What trait?’ – ‘Why, a dog, whenever he sees a stranger, is angry; when an acquaintance, he welcomes him, although the one has never done him any harm, nor the other any good. Did this never strike you as curious?’ – ‘The matter never struck me before; but I quite recognise the truth of your remark.’ – ‘And surely this instinct of the dog is very charming; – your dog is a true philosopher.’ – ‘Why?’ – ‘Why, because he distinguishes the face of a friend and of an enemy only by the criterion of knowing and not knowing. And must not an animal be a lover of learning who determines what he likes and dislikes by the test of knowledge and ignorance?’ – ‘Most assuredly.’ (tr. Benjamin Jowett)