The element of truth in all this, which people are so ready to disavow, is that men are not gentle creatures who want to be loved, and who at the most can defend themselves if they are attacked; they are, on the contrary, creatures among whose instinctual endowments is to be reckoned a powerful share of aggressiveness. As a result, their neighbor is for them not only a potential helper or sexual object, but also someone who tempts them to satisfy their aggressiveness on him, to exploit his capacity for work without compensation, to use him sexually without his consent, to seize his possessions, to humiliate him, to cause him pain, to torture and to kill him.... Who, in the face of all his experience of life and of history, will have the courage to dispute this assertion? As a rule this cruel aggressiveness waits for some provocation or puts itself at the service of some other purpose, whose goal might also have been reached by milder measures. In circumstances that are favorable to it, when the mental counter-forces which normally inhibit it are out of action, it also manifests itself spontaneously and reveals man as a savage beast to whom consideration towards his own kind is something alien. Anyone who calls to mind the atrocities committed during racial migrations or the invasions of the Huns, or by the people known as Mongols under Jenghiz Khan and Tamerlane, or at the capture of Jerusalem by the pious Crusaders, or even, indeed, the horrors of the recent World War -- anyone who calls these things to mind will have to bow humbly before the truth of this view.
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 neighbor and which forces civilization into such a high expenditure. 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. Hence, therefore, the use of methods intended to incite people into identifications and aim-inhibited relationships of love, hence the restriction upon sexual life, and hence too ideal's commandment to love one's neighbor as oneself -- a commandment which is really justified by the fact that nothing else runs so strongly counter to the original nature of man. In spite of every effort, these endeavors of civilization have not so far achieved very much. It hopes to prevent the crudest excesses of brutal violence by itself assuming the right to use violence against criminals, but the law is not able to lay hold of the more cautious and refined manifestations of human aggressiveness.
The fateful question for the human species seems to me to be whether and to what extent their cultural development will succeed in mastering the disturbance of their communal life by the human instinct of aggression and self-destruction. It may be that in this respect precisely the present time deserves a special interest. Men have gained control over the forces of nature to such an extent that with their help they would have no difficulty in exterminating one another to the last man. But who can foresee with what success and with what result?