Leukippos of Elea or Miletos (for both accounts are given of him) had associated with Parmenides in philosophy. He did not, however, follow the same path in his explanation of things as Parmenides and Xenophanes did, but, as is believed, the very opposite (R. P. 185). They made the All one, immovable, uncreated, and finite, and did not even permit us to search for _what is not_; he assumed innumerable and ever-moving elements, namely, the atoms. And he made their forms infinite in number, since there was no reason why they should be of one kind rather than another, and because he saw that there was unceasing becoming and change in things. He held, further, that _what is_ is no more real than _what is not_, and that both are alike causes of the things that come into being; for he laid down that the substance of the atoms was compact and full, and he called them _what is_, while they moved in the void which he called _what is not_, but affirmed to be just as real as _what is_. R. P. 194. [Sidenote: Leukippos and the Eleatics.] 173. It will be observed that Theophrastos, while noting the affiliation of Leukippos to the Eleatic school, points out that his theory is, _prima facie_,[935] just the opposite of that maintained by Parmenides. Some have been led by this to deny the Eleaticism of Leukippos altogether; but this denial is really based on the view that the system of Parmenides was “metaphysical,” coupled with a great reluctance to admit that so scientific a hypothesis as the atomic theory can have had a “metaphysical” origin. It is really due to prejudice, and we must not suppose Theophrastos himself believed the two theories to be so far apart as they seem.[936] As this is really the most important point in the history of early Greek philosophy, and as, rightly understood, it furnishes the key to the whole development, it is worth while to transcribe a passage of Aristotle[937] which explains the historical connexion in a way that leaves nothing to be desired. Footnote 935: The words ὡς δοκεῖ do not imply assent to the view introduced by them; indeed they are used, far more often than not, in reference to beliefs which the writer does not accept. The translation “methinks” in Gomperz, _Greek Thinkers_, vol. i. p. 345, is therefore most misleading, and there is no justification for Brieger’s statement (_Hermes_, xxxvi. p. 165) that Theophrastos dissents from Aristotle’s view as given in the passage about to be quoted. We should be saved from many errors if we accustomed ourselves to translate δοκεῖ by “is thought” or “is believed” instead of by “seems.”