It is no wonder if, under the pressure of these possibilities of suffering, humanity is wont to reduce its demands for happiness, just as even the pleasure-principle itself changes into the more accommodating reality-principle under the influence of external environment; if a man thinks himself happy if he has merely escaped unhappiness or weathered trouble; if in general the task of avoiding pain forces that of obtaining pleasure into the background. Reflection shows that there are very different ways of attempting to perform this task; and all these ways have been recommended by the various schools of wisdom in the art of life and put into practice by men. Unbridled gratification of all desires forces itself into the foreground as the most alluring guiding principle in life, but it entails preferring enjoyment to caution and penalizes itself after short indulgence. The other methods, in which avoidance of pain is the main motive, are differentiated according to the source of the suffering against which they are mainly directed. Some of these measures are extreme and some moderate, some are one-sided and some deal with several aspects of the matter at once. Voluntary loneliness, isolation from others, is the readiest safeguard against the unhappiness that may arise out of human relations. We know what this means: the happiness found along this path is that of peace. Against the dreaded outer world one can defend oneself only by turning away in some other direction, if the difficulty is to be solved single-handed. There is indeed another and a better way: that of combining with the rest of the human community and taking up the attack on nature, thus forcing it to obey human will, under the guidance of science. One is working then with all for the good of all. But the most interesting methods for averting pain are those which aim at influencing the organism itself. In the last analysis all pain is but sensation; it only exists in so far as we feel it, and we feel it only in consequence of certain characteristics of our organism.