This volume describes in condensed but detailed form Freuds development of the theory of instincts. As is well known, Freud reformulated and amplified his theory of instincts at several points during his lifetime. In this volume the reader will be able to follow the development of Freuds thought from his initial discovery of the duality of'sexual' and 'ego instincts' and his recognition of the fundamental importance of the aggressive forces in human nature and behaviour, to the formulation of his theories regarding life and death.