Every economic function comes in contact with the mental life of man, first from the fact that the work is produced by the psyche of personalities. This gave us the material for the first two parts of our discussion. We asked what mind is best fitted for the particular kind of work, and how the mind can be led to the best output of work. But it is evident that the real meaning of the economic process expresses itself in an entirely different contact between work and mind. The economic activity is separated from all other processes in the world, not by the fact that it involves labor and achievement by personalities, but by the fact that this labor satisfies a certain group of human desires which we acknowledge as economic. The mere performance of labor, with all the psychical traits of attention and fatigue and will-impulses and personal qualities, does not in itself constitute anything of economic value. For instance, the sportsman who climbs a glacier also performs such a fatiguing activity which demands the greatest effort of attention and will; and yet the psychotechnics of sport do not belong in economic psychology, because this mountain climbing does not satisfy economic desires. The ultimate characteristic which designates an activity as economic is accordingly a certain effect on human souls. The whole whirl of the economic world is ultimately controlled by the purpose of satisfying certain psychical desires. Hence this psychical effect is still more fundamental for the economic process than its psychical origin in the mental conditions of the worker. The task of psychotechnics is accordingly to determine by exact psychological experiments how this mental effect, the satisfaction of economic desires, can be secured in the quickest, in the easiest, in the safest, in the most enduring, and in the most satisfactory way.