Dualism as an a priori in the perception and conception of reality by humans is introduced and related to the capacity to imagine the continued existence of a lost object in a space other than the one given to the senses (presence–absence). This mental maneuver alleviates the anxieties resulting from a break in the continuity of existence. The emergence of the concept of the psyche is then examined and traced from its early form in Homer to its fully psychological status as the tripartite Platonic soul. As Mythos yields to Logos, conflict is internalized as an opposition between different agencies within the psyche.