" We have all found by experience that it is especially difficult for an obsessional neurotic to carry out the fundamental rule of psycho-analysis. [...] While he is engaged in thinking, his ego has to keep off too much—the intrusion of unconscious phantasies and the manifestation of ambivalent trends. It must not relax, but is constantly prepared for a struggle. "

― Sigmund Freud , Inhibitions, Symptoms and Anxiety