ABSTRACT
Inquiry into the beginnings of a tradition of philosophical thought inevitably brings with it the realization that certain concepts which are now more or less familiar to psychologists were once not understood at all. The word aesthesis, which is used prolifically in Plato and Aristotle to mean ‘sensation’ or ‘perception’, is a word which originated in the 5 th century B.C. The question whether a philosopher possesses a given concept is a difficult one, and while the use of the corresponding word is an indication in that direction, it is not a sure indication. In the field of sense-perception, the situation is more complicated still. Even when the Greek philosophers came to use the word aesthesis they tended to use it in a variety of different ways. In Presocratic thought it is possible to trace a development through the first two stages of the evolution of the concepts of sensation and perception, and a partial move into the third stage.
