For most men, save the scientific workers, science is a mystery in the hands of initiates, who have become adepts in virtue of following ritualistic ceremonies from which the profane herd is excluded. They are fortunate who get as far as a sympathetic appreciation of the methods which give pattern to the complicated apparatus: methods of analytic, experimental observation, mathematical formulation and deduction, constant and elaborate check and test. For most persons, the reality of the apparatus is found only in its embodiments in practical affairs, in mechanical devices and in techniques which touch life as it is lived. For them, electricity is _known_ by means of the telephones, bells and lights they use, by the generators and magnetos in the automobiles they drive, by the trolley cars in which they ride. The physiology and biology they are acquainted with is that they have learned in taking precautions against germs and from the physicians they depend upon for health. The science of what might be supposed to be closest to them, of human nature, was for them an esoteric mystery until it was applied in advertising, salesmanship and personnel selection and management, and until, through psychiatry, it spilled over into life and popular consciousness, through its bearings upon “nerves,” the morbidities and common forms of crankiness which make it difficult for persons to get along with one another and with themselves. Even now, popular psychology is a mass of cant, of slush and of superstition worthy of the most flourishing days of the medicine man.