Erich Fromm (1900-1980) is widely regarded as one of the most important psychoanalytical thinkers of the 20th century. Besides his influence on modern psychology, he was also a key member of the Frankfurt School, and became one of the founders of the socialist humanist movement. He is the author of To Have Or To Be? and Marx's Concept of Man, both published in the Bloomsbury Revelations series.