Rank's uniqueness as a psychologist and psychoanalyst lies in his erudition and knowledge of culture, which made him constantly aware of the social dimension in human development. At the same time his emphasis on individuation made him the forerunner of ego psychology. He is a humanistic process thinker who advances a concept of social relativism; his concern with the very nature of existence challenges all dogmatic interpretations of the human situation and his belief in man's creative potential profoundly affects his philosophy of life and therapy.