The relation between mind and body in human being has hitherto been studied chiefly from the dualistic standpoint. In Descartes' philosophy, which has greatly contributed to the philosophical foundation of the psycho-physical dualism, cogitatio was regarded as an act of pure spirit, while human being was thought to be a complex of mind and body, though these, each in itself, were treated as separate substances. This mode of thinking seems to find acceptance even with some modern philosophers. In Husserl's phenomenology pure consciousness with its intentional structure is distinguished from the human being qua psycho-physical (natural being). Heidegger determines existence as a total being abstracted from the relation between mind and body. ...