§23.1Fr. 23
Ἐν τῷ τεσσαρεσκαιδεκάτῳ τῶν Φυσικῶν οὕτως περὶ τῆς κινήσεως· Τὸν μὲν κοινὸν καὶ καθόλου λόγον οὐ χαλεπὸν ἀποδοῦναι καὶ εἰπεῖν ὡς ἐνέργειά τίς ἐστιν ἀτελὴς τοῦ δυνάμει ὄντος, ᾗ τοιοῦτον καθʼ ἕκαστον γένος τῶν κατηγοριῶν, ὃ καὶ διὰ τῆς αἰσθήσεως σχεδὸν φαίνεται.
Fr. 23 In the fourteenth book of the *Physics*, he writes as follows concerning motion: "It is not difficult to render and state the common and universal definition, namely that it is a certain incomplete activity of that which exists potentially, insofar as it is such, according to each genus of the categories, which is also almost apparent through perception."