What was Freud thinking, when, and why and what were the major influences which shaped his ideas? We follow the inner movement of his theory construction, its meaning and coherence, as well as his conceptual logic and personal directions concerning his evolving views of the reciprocal interactions between mind and body, the motivational force of instinctual drives, and the dominant role of sexuality rooted in evolutionary biology in human development, behaviour, and the creation of neurotic disturbances. We follow Freud’s construction and sequential reconstructions of his theoretical models concerning the nature, dynamics, and principles of unconscious mental functioning, including his changing concepts on the nature and purpose of dreams. We trace his changing views on the role of deferred action of early childhood experiences and the determining role of unconscious fantasy, psychic reality, in the formation of adult character structure and neuroses. Through such historical analysis this book provides grounding for a meaningful understanding of Freud’s familiar concepts: id, ego, superego, and the Oedipus complex. We explore what these concepts meant to Freud, why he conceived them, and what functions they served in his theory of mind. This is the perfect book for students and trainees wanting to learn more about the development of Freud’s ideas, as well as for established psychoanalysts and psychotherapists interested in expanding their knowledge of Freud’s theories.