Instinct and the Unconscious (1920) by

William Halse Rivers Rivers, FRCP, FRS, (12 March 1864 - 4 June 1922) was an English anthropologist, neurologist, ethnologist and psychiatrist, best known for his work treating First World War officers who were suffering from shell shock. Rivers's most famous patient was the poet Siegfried Sassoon, with whom he remained close friends until his own sudden death. Rivers was a fellow of St John's College, Cambridge, and is also notable for his participation in the Torres Straits expedition of 1898 and his consequent seminal work on the subject of kinship.