But in all these new efforts the psychologist meets a certain public resistance, or at least a certain disregard, which he is not accustomed to find in his routine endeavours. As long as he was simply studying the laws of the mind, he enjoyed the approval of the wider public. His work was appreciated as is that of the biologist and the chemist. But when it becomes his aim to discover mental features of the individual, and to foresee what he can expect from the social groups of men, every layman tells him condescendingly that it is a superfluous task, as instinct and intuition and the naïve psychology of the street will be more successful than any measurements with chronoscopes and kymographs. Do we not know how the skilful politician or the efficient manager looks through the mind of a man at the first glance? The life insurance agent has hardly entered the door before he knows how this particular mind must be handled. Every commercial traveller knows more than any psychologist can tell him, and even the waiter in the restaurant foresees when the guest sits down how large a tip he can expect from him. In itself it would hardly be convincing to claim that scientific efforts to bring a process down to exact principles are unnecessary because the process can be performed by instinct. We all can walk without needing a knowledge of the muscles which are used, and can find nourishment without knowing the physiology of nutrition. Yet the physiologist has not only brought to light the principles according to which we actually eat, but he has been able to make significant suggestions for improved diet, and in not a few cases his knowledge can render services which no instinctive appetite could replace. The psychological study of human traits, too, may not only find out the principles underlying the ordinary knowledge of men, but may discover means for an insight which goes as far beyond the instinctive understanding of man as the scientific diet prescribed by a physician goes beyond the fancies of a cook. The manager may believe that he can recognize at the first glance for which kind of work the labourer is fit: and yet the psychological analysis with the methods of exact experiments may easily demonstrate that his judgment is entirely mistaken. Moreover, although such practical psychologists of the street or of the office may develop a certain art of recognizing particular features in the individual, they cannot formulate the laws and cannot lay down those permanent relations from which others may learn.