158. That Zeno’s dialectic was mainly directed against the Pythagoreans is certainly suggested by Plato’s statement, that it was addressed to the adversaries of Parmenides, who held that things were “a many.”[872] Zeller holds, indeed, that it was merely the popular form of the belief that things are many that Zeno set himself to confute;[873] but it is surely not true that ordinary people believe things to be “a many” in the sense required. Plato tells us that the premisses of Zeno’s arguments were the beliefs of the adversaries of Parmenides, and the postulate from which all his contradictions are derived is the view that space, and therefore body, is made up of a number of discrete units, which is just the Pythagorean doctrine. Nor is it at all probable that Anaxagoras is aimed at.[874] We know from Plato that Zeno’s book was the work of his youth.[875] Suppose even that it was written when he was thirty, that is to say, about 459 B.C., Anaxagoras had just taken up his abode at Athens at that time,[876] and it is very unlikely that Zeno had ever heard of him. There is, on the other hand, a great deal to be said for the view that Anaxagoras had read the work of Zeno, and that his emphatic adhesion to the doctrine of infinite divisibility was due to the criticism of his younger contemporary.[877] Footnote 872: The view that Zeno’s arguments were directed against Pythagoreanism has been maintained in recent times by Tannery (_Science hellène_, pp. 249 sqq.), and Bäumker (_Das Problem der Materie_, pp. 60 sqq.). Footnote 873: Zeller, p. 589 (Eng. trans. p. 612). Footnote 874: This is the view of Stallbaum in his edition of the _Parmenides_ (pp. 25 sqq.). Footnote 875: _Parm._, _loc. cit._ Footnote 876: Chap. VI. § 120. Footnote 877: Cf. for instance Anaxagoras, fr. 3, with Zeno, fr. 2; and Anaxagoras, fr. 5, with Zeno, fr. 3. It will be noted how much clearer the historical position of Zeno becomes if we follow Plato in assigning him to a somewhat later date than is usual. We have first Parmenides, then the pluralists, and then the criticism of Zeno. This, at any rate, seems to have been the view which Aristotle took of the historical development.[878] Footnote 878: Arist. _Phys._ Α, 3. 187 a 1 (R. P. 134 b). See below, § 173. [Sidenote: What is the unit?]