The existence of this inclination to aggression，which we can detect in ourselves and justly assume to be present in others，is the factor which disturbs our relations with our neighbour and which forces civilization into such a high expenditure[of energy]. In consequence of this primary mutual hostility of human beings， civilized society is perpetually threatened with disintegration. The interest of work in common would not hold it together， instinctual passions are stronger than reasonable interests. Civilization has to use its utmost efforts in order to set limits to man’s aggressive instincts and to hold the manifestations of them in check by psychical reaction-formations....Civilization is a process in the service of Eros， whose purpose is to combine single human individuals， and after that families， then races， peoples and nations， into one great unity， the unity of mankind.......But man’s natural aggressive instinct，the hostility of each against all and of all against each， opposes this programme of civilization.