I now can comment on another of your statements. You are amazed that it is so easy to infect men with the war-fever, and you surmise that man has in him an active instinct for hatred and destruction, amenable to such stimulations. I entirely agree with you. I believe in the existence of this instinct and have been recently at pains to study its manifestations. In this connection may I set out a fragment of that knowledge of the instincts, which we psychoanalysts, after so many tentative essays and gropings in the dark, have compassed? We assume that human instincts are of two kinds: those that conserve and unify, which we call “erotic” (in the meaning Plato gives to Eros in his Symposium), or else “sexual” (explicitly extending the popular connotation of “sex”); and, secondly, the instincts to destroy and kill, which we assimilate as the aggressive or destructive instincts. These are, as you perceive, the well-known opposites, Love and Hate, transformed into theoretical entities; they are, perhaps, another aspect of those eternal polarities, attraction and repulsion, which fall within your province. But we must be wary of passing overhastily to the notions of good and evil. Each of these instincts is every bit as indispensable as its opposite and all the phenomena of life derive from their activity, whether they work in concert or in opposition. It seems that an instinct of either category can operate but rarely in isolation; it is always blended (“alloyed,” as we say) with a certain dosage of its opposite, which modifies its aim or even, in certain circumstances, is a prime condition of its attainment. Thus the instinct of self-preservation is certainly of an erotic nature, but to gain its ends this very instinct necessitates aggressive action. In the same way the love-instinct, when directed to a specific object, calls for an admixture of the acquisitive instinct if it is to enter into effective possession of that object. It is the difficulty of isolating the two kinds of instinct in their manifestations that has so long prevented us from recognizing them.
If you will travel with me a little further on this road, you will find that human affairs are complicated in yet another way. Only exceptionally does an action follow on the stimulus of a single instinct, which is per se a blend of Eros and destructiveness. As a rule several motives of similar composition concur to bring about the act. This fact was duly noted by a colleague of yours, Professor G. C. Lichtenberg, sometime Professor of Physics at Göttingen; he was perhaps even more eminent as a psychologist than as a physical scientist. He evolved the notion of a “Compasscard of Motives” and wrote: “The efficient motives impelling man to act can be classified like the 32 Winds, and described in the same manner; e.g. Food-Food-Fame or Fame-Fame-Food.” Thus, when a nation is summoned to engage in war, a whole gamut of human motives may respond to this appeal; high and low motives, some openly avowed, others slurred over. The lust for aggression and destruction is certainly included; the innumerable cruelties of history and daily life confirm its prevalence and strength. The stimulation of these destructive impulses by appeals to idealism and the erotic instinct naturally facilitates their release. Musing on the atrocities recorded on history’s page, we feel that the ideal motive has often served as a camouflage for the lust of destruction; sometimes, as with the cruelties of the Inquisition, it seems that, while the ideal motives occupied the foreground of consciousness, they drew their strength from the destructive instincts submerged in the unconscious. Both interpretations are feasible.
You are interested, I know, in the prevention of war, not in our theories, and I keep this fact in mind. Yet I would like to dwell a little longer on this destructive instinct which is seldom given the attention that its importance warrants. With the least of speculative efforts we are led to conclude that this instinct functions in every living being, striving to work its ruin and reduce life to its primal state of inert matter. Indeed it might well be called the “death-instinct”; whereas the erotic instincts vouch for the struggle to live on. The death instinct becomes an impulse to destruction when, with the aid of certain organs, it directs its action outwards, against external objects. The living being, that is to say, defends its own existence by destroying foreign bodies. But, in one of its activities, the death instinct is operative within the living being and we have sought to trace back a number of normal and pathological phenomena to this introversion of the destructive instinct. We have even committed the heresy of explaining the origin of human conscience by some such “turning inward” of the aggressive impulse. Obviously when this internal tendency operates on too large a scale, it is no trivial matter, rather a positively morbid state of things; whereas the diversion of the destructive impulse towards the external world must have beneficial effects. Here is then the biological justification for all those vile, pernicious propensities which we now are combating. We can but own that they are really more akin to nature than this our stand against them, which, in fact, remains to be accounted for.
All this may give you the impression that our theories amount to a species of mythology and a gloomy one at that! But does not every natural science lead ultimately to this—a sort of mythology? Is it otherwise today with your physical science