Philosphic inquiry took two distinct approaches in searching truth. The first one recognized the precedence of nature and the second of logic.The natural approach took the lead in the course of time through Thales and later with Democritus, but it suffered a recession by the revolutionary teaching of Socrates, Plato and partly of Aristotle, who gave precedence to logic and its ideas. Soon though the theory of Platonic ideas was abandoned and the tradition of Ionian science of Thales was reviving supported by Epicurus and Aristotle who in the later part of his life turned to the study of biology.
This historic evolution of philosophical thought had the immediate effect to create a competition between Nature and Reason for the command of philosophic attention. Epicurus the last of the eminent philosophers of antiquity denied the existence of Platonic ideas on the ground that the only existences were atoms and empty space. Thus to his thinking man stood face to face with physical reality primarily through his senses and secondary through his logic. For if we assume that a human being has been deprived of all his five senses, this is tantamount to death and the person has ceased to be a rational creature; the possession of sensation (and additionally of feeling and anticipation) seems to be construed as antecedent to rational activity.