Chapter 14

There are four ways in which a thing is said to be property. In the first place, that is said to be a property which is in one species only but not in the entire species. Such, for example, is the ability which man has for land-surveying, for only man surveys land, yet not every man does have this ability. Secondly, that is said to be a property which belongs to the entire species but not to just one species. An example would be the having of two feet. Thus, every man is a biped, but not man only, because the dove is a biped, too, and so are others of the sort. Thirdly, that is said to be a property which is in the whole species and in it alone but not always. Such is the becoming gray-haired in man, because this is proper to every man and to man alone, yet not always, but only in old age. Fourthly, that is said to be a property which arises from the combination of the first three, namely, that which is in an entire species, is in that species only and always, and is convertible like laughter in man, neighing in the horse, and so on. For only man can laugh and every man can laugh and can always do so, even though he may not always exercise this power. (Thus, if something is a man, it most certainly can laugh; and if something can laugh, it is most certainly a man. And that is what is meant by being convertible. It is with this last meaning that the philosophers are concerned.) Now, to describe it we say that a property is that which belongs to a single species, to the whole species, and always. This has a threefold division: being from the way a thing is formed, that is to say, the way it is shaped, as is the being broad-nailed and walking erect in man; being from the operation of the thing, as the being carried upward which is proper to fire; or being from the potentiality of the thing, as we say that the fire has a power of heating which exceeds the heat of other bodies. The property, moreover, is said to be added over and above the essence, or adventitious.

{Περὶ ἰδίου.} Τὸ ἴδιον τετραχῶς λέγεται. Πρῶτον, ὃ μόνῳ μὲν ὑπάρχει τῷ εἴδει, οὐ παντὶ δέ, ὥσπερ τὸ γεωμετρεῖν τῷ ἀνθρώπῳ: μόνος γὰρ ὁ ἄνθρωπος γεωμέτρης, ἀλλ' οὐ πᾶς ἄνθρωπος γεωμέτρης. Δεύτερον, ὅπερ παντὶ μὲν τῷ εἴδει ὑπάρχει, οὐ μόνῳ δέ, ὡς τὸ δίπουν: πᾶς γὰρ ἄνθρωπος δίπους, οὐ μόνον δὲ ἄνθρωπος δίπους ἀλλὰ καὶ περιστερὰ καὶ τὰ τοιαῦτα. Τρίτον, ὅπερ παντὶ μὲν καὶ μόνῳ, οὐκ ἀεὶ δέ, ὥσπερ τὸ πολιοῦσθαι τῷ ἀνθρώπῳ: τοῦτο γὰρ παντὶ μὲν καὶ μόνῳ ἀνθρώπῳ ἁρμόζει, οὐκ ἀεὶ δὲ ἀλλ' ἐν τῷ γήρᾳ. Τέταρτον, ὅπερ γίνεται τῶν τριῶν τῶν πρώτων συνερχομένων, τουτέστι παντὶ καὶ μόνῳ καὶ ἀεί, ὅπερ καὶ ἀντιστρέφει, ὥσπερ τὸ γελαστικὸν τῷ ἀνθρώπῳ καὶ τὸ χρεμετιστικὸν τῷ ἵππῳ καὶ τὰ τοιαῦτα: μόνος γὰρ ἄνθρωπος ἔχει τὸ γελαστικὸν καὶ πᾶς ἄνθρωπος καὶ ἀεί, εἰ καὶ μὴ ἀεὶ κέχρηται αὐτῷ. Εἴ τι γὰρ ἄνθρωπος, πάντως γελαστικόν, καὶ εἴ τι γελαστικόν, πάντως ἄνθρωπος. Τοῦτό ἐστι τὸ ἀντιστρέφειν. Περὶ τούτου τοῦ σημαινομένου παρὰ τοῖς φιλοσόφοις ὁ λόγος. Ὃ καὶ ὑπογράφοντές φαμεν: Ἴδιόν ἐστι, ὃ παντὶ καὶ μόνῳ τῷ εἴδει καὶ ἀεὶ ὑπάρχει. Τοῦτο δὲ τριχῶς διαιροῦσιν: ἀπὸ τῆς διοργανώσεως τουτέστι διαπλάσεως, ὡς τὸ πλατυώνυχον καὶ τὸ ὀρθοπεριπατητικὸν τῷ ἀνθρώπῳ: ἀπὸ τῆς ἐνεργείας, ὡς τῷ πυρὶ τὸ ἀνωτάτω φέρεσθαι: ἀπὸ τῆς δυνάμεως, ὡς λέγομεν τῷ πυρὶ ὑπάρχειν τὴν θερμαντικὴν δύναμιν ὑπερβάλλουσαν τὰς τῶν ἄλλων σωμάτων θερμότητας. Λέγεται δὲ τὸ ἴδιον ἐπουσιῶδες.