From preface:
"Of all disciplines necessary to the criminal justice in addition to the knowledge of law, the most important are those derived from psychology. For such sciences teach him to know the type of man it is his business to deal with. Now psychological sciences appear in various forms. There is a native psychology, a keenness of vision given in the march of experience, to a few fortunate persons, who see rightly without having learned the laws which determine the course of events, or without being even conscious of them. Of this native psychological power many men show traces, but very few indeed are possessed of as much as criminalists intrinsically require. In the colleges and pre-professional schools we jurists may acquire a little scientific psychology as a ``philosophical propaedeutic,'' but we all know how insufficient it is and how little of it endures in the business of life. And we had rather not reckon up the number of criminalists who, seeing this insufficiency, pursue serious psychological investigations."
An excerpt:
"...Alarming oneself is not performed by words, but by the reciprocal influence of word and gesture, and the power of that influence is observable in the large number of cases where, in the end, people themselves believe what they have invented. If they are of delicate spiritual equilibrium they even become hypochondriacs. Writing, and the reading of writing, is to be considered in the same way as gesticulation; it has the same alarming influence on voice and general appearance as the other, so that it is relatively indifferent whether a man speaks and acts or writes and thinks. This fact is well known to everybody who has ever in his life written a really coarse letter.
Now this exciting gesticulation can be very easily observed, but the observation must not come too late. If the witness is once quite lost in it and sufficiently excited by the concomitant speeches he will make his gestures well and naturally and the artificial and untrue will not be discoverable. But this is not the case in the beginning; then his gestures are actually not skilful, and at that point a definite force of will and rather notable exaggerations are observable; the gestures go further than the words, and that is a matter not difficult to recognize. As soon as the recognition is made it becomes necessary to examine whether a certain congruity invariably manifests itself between word and gesture, inasmuch as with many people the above-mentioned lack of congruity is habitual and honest. This is particularly the case with people who are somewhat theatrical and hence gesticulate too much. But if word and gesture soon conform one to another, especially after a rather lively presentation, you may be certain that the subject has skilfully worked himself into his alarm or whatever it is he wanted to manifest. Quite apart from the importance of seeing such a matter clearly the interest of the work is a rich reward for the labor involved..."
