The relations of Leukippos to Empedokles and Anaxagoras are more difficult to determine. It has become part of the case for the historical reality of Leukippos that there are traces of atomism in the systems of these men; but the case is strong enough without that assumption. Besides, it lands us in serious difficulties, not the least of which is that it would require us to regard Empedokles and Anaxagoras as mere eclectics like Diogenes of Apollonia.[931] The strongest argument for the view that Leukippos influenced Empedokles is that drawn from the doctrine of “pores”; but we have seen that this originated with Alkmaion, and it is therefore more probable that Leukippos derived it from Empedokles.[932] We have seen too that Zeno probably wrote against Empedokles, and we know that he influenced Leukippos.[933] Nor, is it at all probable that Anaxagoras knew anything of the theory of Leukippos. It is true that he denied the existence of the void; but it does not follow that any one had already maintained that doctrine in the atomist sense. The early Pythagoreans had spoken of a void too, though they had confused it with atmospheric air; and the experiments of Anaxagoras with the _klepsydra_ and the inflated skins would only have had any point if they were directed against the Pythagorean theory.[934] If he had really wished to refute Leukippos, he would have had to use arguments of a very different kind. Footnote 931: This point is important, though the argument is weakened by Brieger’s overstatement of it in _Hermes_, xxxvi. p. 183. He says that to assume such a reaction as Anaxagoreanism after the atomic system had once been discovered would be something unexampled in the history of Greek philosophy. Diogenes of Apollonia proves the contrary. The real point is that Empedokles and Anaxagoras were men of a different stamp. So far as Empedokles is concerned, Gomperz states the case rightly (_Greek Thinkers_, vol. i. p. 560). Footnote 932: See above, Chap. V. p. 224, _n._ 492; and Brieger in _Hermes_, xxxvi. p. 171. Footnote 933: Diels (formerly at least) maintained both these things. See above, p. 359, _n._ 859; and p. 382, _n._ 930. If, as seems probable (§ 158), Zeno wrote his book some time between 470 and 460 B.C., Leukippos can hardly have written his before 450 B.C., and even that is too late for him to have influenced Empedokles. It may well have been later still. Footnote 934: See above, Chap. VI. § 131; and Chap. VII. § 145. [Sidenote: Theophrastos on the atomic theory.] 172. Theophrastos wrote of Leukippos as follows in the First Book of his _Opinions_:—