ABSTRACT
§ 1 . Before Plato we observe in all statements about the nature and function of soul a combination of crude observation with deductions from general principles. In Plato this method of procedure is still more obvious, and the sphere of its application is enlarged. On the one hand, the metaphysics of thought and motion furnish a double source for a priori assertions; on the other, increased interest in man as a responsible agent demands some account of the psychology of conduct. The more definite severance of one line of thought from another marks the contrast between Aristotle and Plato. Plato has mapped out the whole field of observation; Aristotle diligently works upon the different parts and exhausts the resources of his time in his careful description of the phenomena of psychic life.
