[20] Plato, Sophist. p. 225 C.
Ξένος. — Τοῦ δὲ ἀντιλογικοῦ, τὸ μὲν ὅσον περὶ τὰ ξυμβολαῖα ἀμφισβητεῖται μέν, εἰκῆ δὲ καὶ ἀτεχνῶς περὶ αὐτὸ πράττεται, ταῦτα θετέον μὲν εἶδος, ἐπείπερ αὐτὸ διέγνωκεν ὡς ἕτερον ὂν ὁ λόγος· ἀτὰρ ἐπωνυμίας οὔθ’ ὑπὸ τῶν ἔμπροσθεν ἔτυχεν, οὔτε νῦν ὑφ’ ἡμῶν τυχεῖν ἄξιον.
Θεαιτητ. — Ἀληθῆ· κατὰ σμικρὰ γὰρ λίαν καὶ παντοδαπὰ διῄρηται.
These words illustrate Plato’s view of an εἶδος or species. Any distinguishable attributes, however petty, and however multifarious, might be taken to form a species upon; but if they were petty and multifarious, there was no advantage in bestowing a specific name.
[21] Plato, Sophist. p. 225 C. τὸ δέ γε ἔντεχνον, καὶ περὶ δικαίων αὐτῶν καὶ ἀδίκων καὶ περὶ τῶν ἄλλων ὅλως ἀμφισβητοῦν, ἆρ’ οὐκ ἐριστικὸν αὖ λέγειν εἰθίσμεθα;
[22] Plato, Sophist. p. 225 E.
The Sophist is traced down, from the genus of separating or discriminating art.
There is yet another road of class-distribution which will bring us down to the Sophist. A great number of common arts (carding wool, straining through a sieve, &c.) have, in common, the general attribute of separating matters confounded in a heap. Of separation there are two sorts: you may separate like from like (this has no established name) — or better from worse, which is called purification. Purification is of two sorts: either of body or of mind. In regard to body, the purifying agents are very multifarious, comprising not only men and animals, but also inanimate things: and thus including many varieties which in common estimation are mean, trivial, repulsive, or ludicrous. But all these various sentiments (observes Plato) we must disregard. We must follow out a real analogy wherever it leads us, and recognise a logical affinity wherever we find one; whether the circumstances brought together be vile or venerable, or some of them vile and some venerable, in the eyes of mankind. Our sole purpose is to improve our intelligence. With that view, all particulars are of equal value in our eyes, provided only they exhibit that real likeness which legitimates them as members of the same class — purifiers of body: the correlate of that other class which we now proceed to study — purifiers of mind.[23]
[23] Plato, Sophist. pp. 226-227. 227 A: τῇ τῶν λόγων μεθόδῳ σπογγιστικῆς ἢ φαρμακοποσίας οὐδὲν ἧττον οὐδέ τι μᾶλλον τυγχάνει μέλον, εἰ τὸ μὲν σμικρά, τὸ δὲ μεγάλα ἡμᾶς ὠφελεῖ καθαῖρον. Τοῦ κτήσασθαι γὰρ ἕνεκεν νοῦν πασῶν τεχνῶν τὸ ξυγγενὲς καὶ τὸ μὴ ξυγγενὲς κατανοεῖν πειρωμένη, τιμᾷ πρὸς τοῦτο, ἐξ ἴσου πάσας, καὶ θάτερα τῶν ἑτέρων κατὰ τὴν ὁμοιότητα οὐδὲν ἡγεῖται γελοιότερα, σεμνότερον δέ τι τὸν διὰ στρατημικῆς ἢ φθειριστικῆς δηλοῦντα θηρευτικὴν οὐδὲν νενόμικεν, ἀλλ’ ὡς τὸ πολὺ χαυνότερον. Καὶ δὴ καὶ νῦν, ὅπερ ἤρου, τί προσεροῦμεν ὄνομα ξυμπάσας δυνάμεις, ὅσαι σῶμα εἴτε ἔμψυχον εἴτε ἄψυχον εἰλήχασι καθαίρειν, οὐδὲν αὐτῇ διοίσει, ποῖον τι λεχθὲν εὐπρεπέστατον εἶναι δόξει· μόνον ἐχέτω χωρὶς τῶν τῆς ψυχῆς καθάρσεων πάντα ξυνδῆσαν ὅσα ἄλλο τι καθαίρει. To maintain the equal scientific position of φθειριστική, as two different species under the genus θηρευτική, is a strong illustration.
Compare also Plato, Politikus, p. 266 D.