Psychological Principles

miss in Aristotle is a clear recognition of what we now call consciousness as the central feature of all psychical facts. Regarding these facts as he did from the outside rather than from within, from the circumference rather than from the centre, he failed to find an adequate unity for the diverse functions which he described ; he had to rest content with the biological conception of an organism, into which, however, he infused a strong teleological colouring. Descartes' Psychology of the thinking mind. § 2. When we pass to the psychology of Descartes we are at the opposite extreme. The connexion of body and mind, the corner-stone of Aristotle's construction, was the chief stumbling- block in the way of Descartes' advance, and has remained as a perplexing problem even to our own day. The hazy materialism, into which the Aristotelian psychology had developed in mediaeval times, Descartes banished once for all by the new definitions which he gave of matter and mind. Both were substances and therefore essentially distinct: the essence of matter was extension or the occupation of space, that of mind was consciousness ; and between these there was no common term and there was no natural connexion. Cogito, ergo sum, Descartes began : ' I think, therefore I am.' This was for him the primal certainty, the starting-point alike of his philosophy and of his psychology. " By the word thought (cogitatio)" he tells us, " I understand all that which so takes place in us tha...