During the first ten years of his career in psychological medicine, Sigmund Freud espoused a theory of unconsciousness which predated his own. As Rosemarie Sand describes in The Unconscious without Freud, he would evolve this theory over the course of his career and eventually apply it to his own psychological practice. Once Freud's hypothesis of unconscious mental functioning was published, the same professionals who had valued the traditional concept turned against what they considered to be a catastrophic, logically indefensible revision. The scientific investigation of unconscious...

Freud was right: mind and brain evolved together, adapting progressively to cultural change; responding regressively to wars, genocides, and forced migrations. Freud traced innate conflicts between pleasure and aggression in each stage of individual development to corresponding development in cultural stages. Cultural trauma that induces PTSD with a loss of secure identity in one generation induces collective phantasies (mythologies) among succeeding generations, and this may form cultural syndromes of revenge and restitution. Families, tribes, clans, and religious communities can regress...