Jung's twin brother. Otto Gross and Carl Gustav Jung. With an hitherto unpublished letter by C. G. Jung.

This paper is a preliminary communication of several years of research into the life and work of the Austrian psychoanalyst and anarchist Otto Gross (1877-1920). Although he played a pivotal role in the birth of modernity, acting as a significant influence upon psychiatry, psychoanalysis, ethics, sociology and literature, he has remained virtually unknown to this day. Following a biographical sketch and an overview of his main theoretical contributions, the impact of Gross' life and work on the development of analytical theory and practice is described. His relationship with some of the key figures in psychoanalysis is presented, with particular emphasis on his connections to Jung. The paper concludes with an account of relevant contemporary interest in his work: the founding of the International Otto Gross Society, the first edition of The Collected Works of Otto Gross on the Internet, and the 1st and 2nd International Otto Gross Congresses which took place in Berlin in 1999 and at the Burghölzli Clinic, Zürich, in October 2000.