Instincts and Their Vicissitudes
Written between March 15 and April 4, 1915, and immediately published, Instincts and Their Vicissitudes opens the "collection which I originally intended to publish in book form under the title 'Preliminaries to a Metapsychology.' . . . The intention of the series is to clarify and carry deeper the theoretical assumptions on which a psycho-analytic system could be founded" (Freud, 1917d, p. 222 n.).