Sigmund Freud was the principal theoretician to bring psyche and soma together. He demonstrated the importance of the emotions in producing mental disturbances and somatic disorders. His early psychoanalytic formulations detailed the role of psychic determinism in somatic conversion reactions. Using Freud's insight, a number of workers in the early decades of the 20th century tied to expand the understanding of the interrelationship of psyche and soma.
Benjamin J. Sadock, Virginia A. Sadock, and Pedro Ruiz, Kaplan and Sadock's Synopsis of Psychiatry: Behavioral Sciences/Clinical Psychiatry, 11th ed. (2015), Chap. 13 : Psychosomatic Medicine; p. 465
