[29] Plutarch, De Comm. Notit., xxx., 2; Cicero, Acad., I., xi., 39; Diog., VII., 150; Zeller, p. 117.
[30] Plutarch, De Stoic. Repug., xliii., 4.
[31] Zeller, p. 201, ff.
[32] Cicero, De Nat. Deor., II., xv., 39.
[33] Sextus Empiricus, Adv. Math., IX., 18.
[34] Cicero, De Nat. Deor., I., xiii., 32.
[35] Zeller, p. 309 ff.
[36] See Cicero, De Divinatione, I., passim.
[37] Plutarch, De Placit. Phil., IV., xi.
[38] This seems the best explanation of the various statements on the subject made by our authorities, for which see Zeller, pp. 71-86.