Along with Freud, Jung, Adler, and William James, Wolfgang Kohler, co-founder of Gestalt Psychology, is one of the most valuable and innovative thinkers in modern psychology. Dynamics in Psychology is his most important statement of the application of the Gestalt approach to psychological thinking generally and to perception and memory in particular. He argues here that psychological theories cannot be restricted to the realm of psychology proper, that they must refer to biological and physical concepts. Kohler's scientific precision and continual respect for the whole human being gives his work its lasting value.