[88] The best special illustration of this truth with which I am acquainted is presented for the science of chemistry in an article by F. WALD, "Die Genesis der stöchiometrischen Grundgesetze," in _Zeitschrift für physikalische Chemie_, Vol. XVIII (1895), pp. 337 ff. [89] [Greek: Xi] 201, 246. [90] H 99. [91] In allusion to fr. 90 (DIELS). DIELS finds in fr. 108 (fr. 18, BYWATER), [Greek: oti sophon esti pantôn kechôrismenon] the thought that God is the Absolute, comparing the [Greek: Nous] of Anaxagoras and the [Greek: chôristê idea] of Plato and the [Greek: ousia chôristê] of Aristotle. He assumes that [Greek: sophon]=[Greek: logos] and concedes great significance to the fragment. But this interpretation is utterly incompatible with everything else that we know of Heraclitus, and should be admitted only if it were the only one admissible. ZELLER discusses the fragment at length, Vol. I, p. 629, 1. If Diels's interpretation be accepted, the exposition above given of Heraclitus's logical position must be abandoned. [92] It has been, and in some quarters is still, the fashion to say that Heraclitus is the originator of the doctrine of relativity; but Zeller is quite right in denying the charge. No doubt his teachings lent themselves readily to such a development, but he did not so express himself. According to him the _contrarieties coexist in the process_. [93] _Cf._ RITTER-PRELLER, § 65_c_. [94] This, in a word, is the burden of my study of _The Necessary and the Contingent in the Aristotelian System_. [95] I have in preparation a study of the problem of physical interaction in Pre-Socratic philosophy which deals with this question in all its phases. [96] This statement is, of course, figurative, since Empedocles denied the existence of a void. [97] I cannot now undertake a defense of this statement, which runs counter to certain ancient reports, but must reserve a full discussion for my account of physical interaction. [98] The motive for making this assumption was clearly the desire to make of the [Greek: Nous] the prime mover in the world while exempting it from reaction on the part of the world, which would have been unavoidable if its nature had contained parts of other things. It is the same problem of "touching without being touched in return" that led Aristotle to a similar definition of God and of the rational soul. The same difficulty besets the absolutely "simple" soul of Plato's _Phaedo_ and the causality of the Ideas. [99] ARISTOTLE, _De Generatione et Corruptione_, 323^b 10 f. [100] We have seen that this distinction was latent in Anaximenes's process of rarefaction and condensation. For other matters see CHAIGNET, _Histoire de la Psychologie_, Vol. I, p. 114, whose account, however, needs to be corrected in some particulars. [101] I say "perhaps" because ancient reports differ as to the precise relation of position and arrangement to the distinction between qualities, primary and secondary.