had made for his own purposes, the students of legal psychology adjusted experiments to the particular needs of the courtroom.  Investigations were carried on to determine, the fidelity of testimony or to find methods for the detection of hidden thoughts and so on.  Efforts toward the application of psychology have accordingly grown up in the fields of pedagogy, medicine, and jurisprudence, but as these studies naturally do not remain independent of one another, they all together form the one unified science of applied psychology.[2]

As soon as the independence of this new science was felt, it was natural that new demands and new problems should continue to originate within its own limits.  There must be applied psychology wherever the investigation of mental life can be made serviceable to the tasks of civilization.  Criminal law, education, medicine, certainly do not constitute the totality of civilized life.  It is therefore the duty of the practical psychologist systematically to examine how far other purposes of modern society can be advanced by the new methods of experimental psychology.  There is, for instance, already, far-reaching agreement that the problems of artistic creation, of scientific observation, of social reform, and many similar endeavors must be acknowledged as organic parts of applied psychology.  Only one group of purposes is so far surprisingly neglected in the realm of the psychological laboratory:  the purposes of the economic life, the purposes of commerce and industry, of business and the market in the widest sense of the word.  The question how far applied psychology can be extended in this direction is the topic of the following discussions.

III

MEANS AND ENDS

Applied psychology is evidently to be classed with the technical sciences.  It may be considered as psychotechnics, since we must recognize any science as technical if it teaches us to apply theoretical knowledge for the furtherance of human purposes.  Like all technical sciences, applied psychology tells us what we ought to do if we want to reach certain ends; but we ought to realize at the threshold where the limits of such a technical science lie, as they are easily overlooked, with resulting confusion.  We must understand that every technical science says only:  you must make use of this means, if you wish to reach this or that particular end.  But no technical science can decide within its limits whether the end itself is really a desirable one.  The technical specialist knows how he ought to build a bridge or how he ought to pierce a tunnel, presupposing that the bridge or the tunnel is desired.  But whether they are desirable or not is a question which does not concern the technical scientist, but which must be considered from economic or political or other points, of view.  Everywhere the engineer must know how to reach an end, and must leave it to others