n a certain sense every physician had made use
of a certain amount of psychology in his professional work. He had
always had to make clear to himself the mental experiences of the
patient, to study his pain sensations and his feelings of comfort,
his fears and his hopes, his perceptions and his volitions, and to a
certain degree he had always tried to influence the mental life of the
patient, to work on him by suggestion and to help him by stimulating
his mind. But as far as a real description and explanation of such
mental experiences came in question, all remained a dilettantic
semi-psychology which worked with the most trivial conceptions of
popular thinking. The medical men recognized the disproportion between
the exactitude of their anatomical, physiological, and pathological
observation and the superficiality of their self-made psychology. Thus
the desire arose in their own medical circle to harmonize their
psychological means of diagnosis and therapy with the schemes of
modern scientific psychology. The physician who examines the
sensations in a nervous disease, or the intelligence in a mental
disease, or heals by suggestion or hypnotism, tries to apply the
latest discoveries of the psychological laboratory. But here, too, the
same development as in pedagogy can be traced. The physicians at first
made use only of results which had been secured under entirely
different points of view, but later the experiments were subordinated
to the special medical problems. Then the physician was no longer
obliged simply to use what he happened to find among the results of
the theoretical psychologist, but carried on the experiments in the
service of medical problems. The independent status of experimental
medical psychology could be secured only by this development.

In somewhat narrower limits the same may be said as to the problems of
law. A kind of popular psychology was naturally involved whenever
judges or lawyers analyzed the experience on the witness stand or
discussed the motives of crime or the confessions of the criminal or
the social conditions of criminality. But when every day brought new
discoveries in the psychological laboratory, it seemed natural to make
use of the new methods and of the new results in the interest of the
courtroom. The power of observation in the witness, the exactitude of
his memory, the character of his illusions and imagination, his
suggestibility and his feeling, appeared in a new light i