Chapter 40

The nature of each being is the principle of its motion and repose. The earth, for example, is moved [i.e., ploughed] to make it produce, but, so far as concerns its being moved from place to place, it is at rest, because it is not moved from place to place. Now, the principles and cause of its motion and repose—or that according to which it is of its nature thus moved and rests substantially, that is to say, naturally and not accidentally—is called 'nature' from its 'naturally having being' and existing in such a manner. This is nothing other than substance, because it is from its substance that it has such a potentiality, that is to say, that of motion and repose. The substance, then, is the cause of its motion and repose. Now, 'nature' is so called from its 'naturally having being'.

[26] {Περὶ φύσεως.} Φύσις ἐστὶν ἀρχὴ τῆς ἑκάστου τῶν ὄντων κινήσεώς τε καὶ ἠρεμίας, οἷον ἡ γῆ κινεῖται μὲν κατὰ τὸ βλαστάνειν, ἠρεμεῖ δὲ κατὰ τὴν ἐκ τόπου εἰς τόπον μετάβασιν: οὐ γὰρ κινεῖται ἀπὸ τόπου εἰς τόπον. Ἡ οὖν ἀρχὴ καὶ ἡ αἰτία τῆς κινήσεώς τε καὶ τῆς ἠρεμίας αὐτῆς, καθ' ἣν πέφυκεν οὕτω κινεῖσθαι καὶ ἠρεμεῖν οὐσιωδῶς ἤγουν φυσικῶς καὶ οὐ κατὰ συμβεβηκός, φύσις λέγεται παρὰ τὸ τοιῶσδε πεφυκέναι τε καὶ ὑπάρχειν. Αὕτη δὲ οὐδὲν ἕτερόν ἐστιν εἰ μὴ οὐσία: ἐκ γὰρ τῆς οὐσίας ἔχει τὴν τοιαύτην δύναμιν ἤγουν τὴν κίνησιν καὶ ἠρεμίαν. Καὶ ἡ οὐσία ἐστὶν ἡ αἰτία τῆς κινήσεως αὐτῆς καὶ ἠρεμίας. Λέγεται δὲ φύσις παρὰ τὸ πεφυκέναι.