The universal tendency of the pre-Socratic philosophy is to find some principle for the explanation of nature.
For of all the pre-Socratic philosophers, he speaks of them with the greatest respect.
Moreover, Thales propounded the problem, and determined the direction and character, of all pre-Socratic philosophy.
A few words must be said of the sources of our knowledge of pre-Socratic philosophy.
Many, if not all the elements of the pre-Socratic philosophy are included in the Timaeus.
Haeckel's system is mainly poetico-mythical, chiefly on the lines of some of the pre-Socratic philosophers.
The pre-Socratic philosophies are simpler, and we may observe a progress in them; but is there any regular succession?
He is never able to reconcile the first causes of the pre-Socratic philosophers with the final causes of Socrates himself.