Jung''s discovery of the ''collective unconscious'', a psychic inheritance common to all humankind, transformed the understanding of the self and the way we interpret the world. In <EM>On the Nature of the Psyche</EM> Jung describes this remarkable theory in his own words, and presents a masterly overview of his theories of the unconscious, and its relation to the conscious mind. Also contained in this collection is <EM>On Psychic Energy</EM>, where Jung defends his interpretation of the libido, a key factor in the breakdown of his relations with Freud. For anyone seeking to understand Jung''s insights into the human mind, this volume is essential reading.