In spite of the convenient textbook criteria that specialists set forth, the distinction between the madman and the jealous man is a difficult one. The madman, like the man in love, the jealous man, or the man prey to any overwhelming passion, is a "patient," that is, a passive agent in the grip of a force that seems to be outside himself. Madman and passionate man are both tossed in piteous agitation, immersed in delirium, or plunged into unwholesome reveries. Both derive the greatest harm from an inalterable incapacity to exert self-control. We know too little of the organic determinants of pathologic mental states, but I would wager that when these become clarified, the disturbance will be shown to be the same in paranoia and in the fits of jealousy. Where does jealousy end and paranoia begin?