§68.1Fr. 68
Ἔστιν ὁ τόπος, ὡς λέγει Θ., ἀρχή τις ἢ στοχεῖον ἀφʼ οὗ λαμβάνομεν τὰς περὶ ἕκαστον ἀρχὰς, ἐπιστήσαντες τὴν διάνοιαν, τῇ περιγραφῇ μὲν ὡρισμένως, ἢ γὰρ περιλαμβάνει τὰ κοινά τε καὶ καθόλου ἅ ἐστι τὰ κύρια τῶν συλλογισμῶν, ἢ δύναταί γε ἐξ αὐτῶν τὰ τοιαῦτα δείκνυσθαί τε καὶ λαμβάνεσθαι, - τοῖς δὲ καθʼ ἕκαστα ἀορίστως· ἀπὸ τούτων γὰρ ὁρμώμενον ἔστιν εὐπορεῖν προτάσεως ἐνδόξου πρὸς τὸ προκείμενον· τοῦτο γὰρ ἡ ἀρχή.
A topic (topos) is, as Theophrastus says, a certain principle or element from which we derive the principles concerning each subject by applying our intellect, in outline, indeed, definitely—for it either encompasses the common and universal things which are the principal elements of syllogisms, or at least such things can be demonstrated and derived from them—but in respect of particulars, indefinitely; for starting from these, it is possible to find an abundance of reputable premises for the problem at hand; for this is the principle.