§ 3. SECOND GROUP OF PRE-SOCRATIC SCHOOLS.

7. Dynamism and Mechanicism or Atomism, in General. -- Of the two problems raised by the study of Nature, that of the change of things occupies the attention of the representatives of this second group. Here we meet: (1) Ionic Dynamism, or the theories propounded by the new Ionic School after Heraclitus; and (2) the Mechanicist or Atomist theories of (a) Empedocles, (b) of the Atomist School, (c) of Anaxagoras.

Dynamism is opposed to Mechanicism or Atomism. Both systems were, no doubt, contemporaneous with the earliest speculations of Grecian philosophy, but as they regard the processus of things the exposition of their principles belongs rather to this second phase of Pre-Socratic Cosmology.

In its widest sense, physical dynamism embraces these two propositions: (1) the things of nature develop under the influence of one or more internal principles of activity; (2) where these principles are manifold they differ among themselves qualitatively in the various beings and their phenomena.

The fundamental ideas of atomism can be also reduced to two principles: (1) In the various things of nature there is material mass, and there is motion. The parts of the material mass are qualitatively homogeneous, and their differentiation in size and shape explains the diversity of the various beings and phenomena in the world. This differentiation of parts results from mechanical motion. (2) The motion that animates the various parts of the whole mass of matter is communicated, that is to say, it is not the product of any energy proper to the mass, this latter being inert.