Chapter 37

All things that fall in the same category are generically the same (as man and horse). Generically different are all those that fall in different categories (as animal and knowledge). They are different in genus. On the other hand, all things that come under the same species and thus have their substance in common, as Peter and Paul, are specifically the same. But those are specifically different which differ from one another in species, that is to say, by reason of their substance, as do man and the horse. All those things are numerically different which by the combination of their accidents have marked off for themselves the individuality of their own individual substance and have thus acquired individual existence, that is to say, those that are individuals, such as Peter and Paul and all other individual men.

The differences of all things that are generically different are also specifically different, as, for example, those of animal and knowledge—for the animal comes under substance, whereas knowledge comes under quality. Constituent differences of the animal are the animate and the sentient, whereas the rational, the irrational, the winged, the terrestrial, or the aquatic are dividing differences. On the other hand, constituent differences of knowledge are its inherence in animate rational beings and, besides this, its tendency to inalterability; whereas grammar and philosophy are dividing differences. For to that category to which the genus belongs the species also belongs, and so also do the differences of the species. And nothing prevents the same differences from belonging to the subaltern genera and species, but not all, because, for example, the living cannot make the non-living. Now, by differences here I mean those which constitute the genera and the species.

Moreover, one should know that the nine categories which are not substance, even though they are accidents, do each one have constituent and dividing differences. Each is a most general genus and each has subaltern species and genera and most specific species. For, without exception, where there is a genus, there there are species and dividing differences, since they are what divide the genera into species. And where there are species, there there are differences also, for they are what constitute the species.

The term ‘one’ is used in three ways. Either it will be one in genus, as, for example, we say that man and the horse are generically one and the same, because they belong to one genus, namely, the animal. Or it will be one in species, as we say that, since Socrates and Plato belong to one species, man, they are specifically one and the same. Or it will be one in number, as we say that Socrates is in himself one, being distinct from all other men.

{Περὶ ὁμογενῶν καὶ ὁμοειδῶν ἑτερογενῶν τε καὶ ἑτεροειδῶν καὶ ἀριθμῷ διαφερόντων.} Ὁμογενῆ εἰσιν, ὅσα ὑπὸ τὴν αὐτὴν κατηγορίαν τάσσεται. Ἑτερογενῆ δέ εἰσιν, ὅσα ὑπ' ἄλλην καὶ ἄλλην κατηγορίαν εἰσίν: ταῦτα ἕτερα τῷ γένει εἰσίν. Ὁμοειδῆ δέ εἰσιν, ὅσα ὑπὸ τὸ αὐτὸ εἶδος τάσσεται καὶ κοινωνοῦσι τῷ λόγῳ τῆς οὐσίας ὡς Πέτρος καὶ Παῦλος. Ἑτεροειδῆ εἰσι τὰ τῷ εἴδει διαφέροντα ἀλλήλων ἤγουν ὅσα τῷ λόγῳ τῆς οὐσίας διαφέρουσιν ὡς ἄνθρωπος, ἵππος. Ἀριθμῷ δὲ διαφέρουσιν, ὅσα τῇ συμπλοκῇ τῶν συμβεβηκότων τὴν ἰδιότητα τῆς οἰκείας ὑποστάσεως ἀφωρίσαντο καὶ τὴν καθ' αὑτὸ ἐσχήκασιν ὕπαρξιν ἤγουν τὰ ἄτομα ὡς Πέτρος, Παῦλος καὶ ἕκαστος τῶν ἀνθρώπων. Τῶν πάντῃ ἑτερογενῶν ἕτεραι τῷ εἴδει καὶ αἱ διαφοραὶ οἷον ζῷον καὶ ἐπιστήμη: τὸ μὲν γὰρ ζῷον ὑπὸ τὴν οὐσίαν τελεῖ, ἡ δὲ ἐπιστήμη ὑπὸ τὸ ποιόν. Τοῦ μὲν οὖν ζῴου διαφοραὶ συστατικαὶ μὲν τὸ ἔμψυχον, τὸ αἰσθητικόν, διαιρετικαὶ δὲ τὸ λογικόν, τὸ ἄλογον, τὸ πτηνόν, τὸ ἔνυδρον: τῆς δὲ ἐπιστήμης συστατικαὶ μὲν τὸ τοῖς ἐμψύχοις καὶ λογικοῖς ἐνυπάρχειν, ἔτι δὲ καὶ τὸ δυσμετάβλητον, διαιρετικαὶ δὲ γραμματική, φιλοσοφία. Ἧς γὰρ κατηγορίας ὑπάρχει τὸ γένος, ἐκείνης καὶ τὸ εἶδος καὶ αἱ τοῦ εἴδους διαφοραί: τῶν δὲ ὑπ' ἄλληλα γενῶν τε καὶ εἰδῶν οὐδὲν κωλύει τὰς αὐτὰς εἶναι διαφοράς, εἰ καὶ μὴ πάσας. Διαφορὰς δὲ ἐνταῦθά φημι τὰς συνιστώσας αὐτά. Χρὴ δὲ γινώσκειν, ὅτι αἱ ἐννέα κατηγορίαι αἱ ἐκτὸς τῆς οὐσίας ἔχουσιν ἑκάστη, εἰ καὶ συμβεβηκότα εἰσί, συστατικὰς καὶ διαιρετικὰς διαφορὰς καὶ ἑκάστη αὐτῶν γενικώτατον γένος ἐστὶ καὶ ἔχει καὶ εἴδη καὶ γένη ὑπάλληλα καὶ εἰδικώτατα εἴδη. Πάντως γάρ, ὅτι, ἔνθα γένος, καὶ διαφοραὶ διαιρετικαί εἰσιν: αὗται γάρ εἰσιν αἱ διαιροῦσαι τὰ γένη εἰς εἴδη: καί, ἔνθα εἴδη, εἰσὶ καὶ συστατικαὶ διαφοραί: αὗται γάρ εἰσιν αἱ συνιστῶσαι τὰ εἴδη. Τὸ ἓν τριχῶς λαμβάνεται: ἢ γένει, οἷόν φαμεν ἄνθρωπον καὶ ἵππον ἓν τῷ γένει καὶ ταὐτόν: ὑφ' ἓν γὰρ γένος εἰσίν, ὑπὸ τὸ ζῷον: ἢ εἴδει, ὡς Σωκράτην φαμὲν καὶ Πλάτωνα ὑφ' ἓν εἶδος ὄντας, ὑπὸ τὸν ἄνθρωπον, ἓν εἶναι τῷ εἴδει καὶ ταὐτόν: ἢ ἀριθμῷ, ὡς Σωκράτην φαμὲν ἕνα εἶναι καθ' αὑτὸν τῶν λοιπῶν ἀνθρώπων κεχωρισμένον.