Herbert "Harry" Stack Sullivan was an American neo-Freudian psychiatrist and psychoanalyst who held that "personality can never be isolated from the complex interpersonal relationships in which [a] person lives" and that "[t]he field of psychiatry is the field of interpersonal relations under any and all circumstances in which [such] relations exist". Having studied therapists Sigmund Freud, Adolf Meyer, and William Alanson White, he devoted years of clinical and research work to helping people with psychotic illness.