[155] Here may be noted the objection mentioned by Sext. Math. viii. 463; Pyrrh. ii. 186: The Sceptics cannot deny the possibility of arguing without proving their assertion and thereby practically admitting the possibility. Also another one urged by Antipater against Carneades (Cic. Acad. ii. 9, 28; 34, 109): He who asserts that nothing can be known with certainty must, at least, believe that he can with certainty know this. The replies of the Sceptics to these objections, and the way they turned them in their own favour, will be found in Sext. Math. l.c. and vii. 433. [156] Chrysippus opposed Arcesilaus, with such success, according to the view of the Stoic School, that Carneades was refuted by anticipation; and it was considered a special favour of Providence that the labours of Chrysippus had occupied an intermediate place between two of the most important Sceptics. Plut. Sto. Rep. i. 4, p. 1059. Diog. 198 mentions a treatise against Arcesilaus. [157] Plut. Sto. Rep. 10 (see p. 66, 1); Ibid. 47, 12: καὶ μὴν ἔν γε τοῖς πρὸς τοὺς Ἀκαδημαϊκοὺς ἀγῶσιν ὁ πλεῖστος αὐτῷ τε Χρυσίππῳ καὶ Ἀντιπάτρῳ πόνος γέγονε περὶ τοῦ μήτε πράττειν μήτε ὁρμᾶν ἀσυγκαταθέτως, ἀλλὰ πλάσματα λέγειν καὶ κενὰς ὑποθέσεις τοῦς ἀξιοῦντας οἰκείας φαντασίας γενομένης εὐθὺς ὁρμᾶν μὴ εἴξαντας μηδὲ συγκατατιθεμένους. Ibid. adv. Col. 26, 3, p. 1122: τὴν δὲ περὶ πάντων ἐποχὴν οὐδ’ οἱ πολλὰ πραγματευσάμενοι καὶ κατατείναντες εἰς τοῦτο συγγράμματα καὶ λόγους ἐκίνησαν· ἀλλ’ ἐκ τῆς Στοᾶς αὐτῆς τελευτῶντες ὥσπερ Γοργόνα τὴν ἀπραξίαν ἐπάγοντες ἀπηγόρευσαν. Epict. (Arrian. Diss. i. 27, 15) quietly suppresses a Sceptic by saying: οὐκ ἄγω σχολὴν πρὸς ταῦτα. Following also the Stoic line, Cic. Acad. ii. 10–12, makes Antiochus argue that Scepticism makes all action impossible. [158] In Sext. Math. vii. 244, ἀληθεῖς φαντασίαι are, first of all, literally explained to be φαντασίαι, ὧν ἔστιν ἀληθῆ κατηγορίαν ποιήσασθαι· then, under the head of true φαντασίαι, the καταληπτικαὶ and οὐ καταληπτικαὶ are distinguished, i.e., notions which are accompanied by a clear impression of being true, and such as are not; and, in conclusion, φαντασία καταληπτικὴ is defined: ἡ ἀπὸ τοῦ ὑπάρχοντος καὶ κατ’ αὐτὸ τὸ ὑπάρχον ἐναπομεμαγμένη καὶ ἐναπεσφραγισμένη, ὁποία οὐκ ἂν γένοιτο ἀπὸ μὴ ὑπάρχοντος. This definition is afterwards more fully explained. The same explanation is given Ibid. 402 and 426; viii. 85; Pyrrh. ii. 4; iii. 242; Augustin. c. Acad. ii. 5, 11; Cic. Acad. ii. 6, 18. Diog. vii. 46: τῆς δὲ φαντασίας τὴν μὲν καταληπτικὴν τὴν δὲ ἀκατάληπτον· καταληπτικὴν μὲν, ἣν κριτήριον εἶναι τῶν πραγμάτων φασὶ, τὴν γινομένην ἀπὸ ὑπάρχοντος κατ’ αὐτὸ τὸ ὕπαρχον ἐναπεσφραγισμένην καὶ ἐναπομεμαγμένην· ἀκατάληπτον δὲ τὴν μὴ ἀπὸ ὑπάρχοντος, ἢ ἀπὸ ὑπάρχοντος μὲν, μὴ κατ’ αὐτὸ δὲ τὸ ὑπάρχον, τὴν μὴ τρανῆ μηδὲ ἔκτυπον. Ibid. 50.