§18.1Fr. 18
Ὅλως δὲ ὡς κοινῶς εἰπεῖν ἀπὸ τῶν αἰσθήσεων καὶ τῶν αἰσθητῶν τῶν περὶ τῶν φυσικῶν ἀρχῶν ἀλήθειαν ἀνιχνευτέον καὶ Θεοφράστῳ πειθομένοις ὃς περὶ τούτου ζητῶν ἐν πρώτῳ τῶν Φυσικῶν τάδε γέγραφε· Ἐπεὶ δὲ οὐκ ἄνευ μὲν κινήσεως οὐδὲ περὶ ἑνὸς λεκτέον· πάντα γὰρ ἐν κινήσει τὰ τῆς φύσεως· ἄνευ δὲ ἀλλοιωτικῆς καὶ παθητικῆς οὐχ ὑπὲρ τῶν περὶ τὸ μέσον, εἰς ταῦτά τε καὶ περὶ τούτων λέγοντας οὐχ οἷόν τε καταλιπεῖν τὴν αἴσθησιν ἀλλʼ ἀπὸ ταύτης ἀρχομένους πειρᾶσθαι χρὴ θεωρεῖν ἢ τὰ φαινόμενα λαμβάνοντας καθʼ ἑαυτὰ ἢ ἀπὸ τούτων εἴ τινες ἄρα κυριώτεραι καὶ πρότεραι τούτων ἀρχαί·
Fr. 18 On the whole, to speak generally, the truth about natural principles must be traced from perceptions and perceptible things, also for those who follow Theophrastus, who, investigating this in the first book of his Physics, has written as follows: "Since, on the one hand, one must not speak of even a single thing without motion—for all things of nature are in motion—and, on the other hand, without motion that is alterative and passive, one must not speak of things around the center, for those who direct their words to these things and speak about them, it is impossible to abandon perception; rather, starting from this, one must try to investigate, either by taking the appearances in themselves, or from these, if there are indeed any principles that are more authoritative and prior to them.
καὶ κάλλιον οἶμαι τοιοῦτόν τινα τρόπον τὴν ἀπὸ τῶν ἡμῖν γνωριμωτέρων ἐπὶ τὰς ἀρχὰς ἐπίβασιν γίνεσθαι.
And I think it is better for the approach from what is more knowable to us to the principles to take place in some such manner."