>>696007The great discovery of Freud I would say is that human beings have history. Genetic history, cultural history, personal history, all mutually intertwined. At the bottom of individual subjectivity lies social (and biological ) objectivity. Human psyche is a collection of processes acquired during its development, which happens under concrete circumstances of individual life.
A book I would really recommend if you want to get both defense and critique of psychoanalysis from Marxist perspective is
Social Amnesia: A Critique Of Contemporary Psychology, great read. Its relatively short and will give you general idea of Freud's contribution to marxism.