It is obvious that these two contrary movements of the libido, as simple psychic mechanisms, may play a part alternately in the same individual, since after all they serve the same purpose by different methods--namely, to minister to his well-being. Freud has taught us that in the mechanism of hysterical transference the individual aims at getting rid of disagreeable memories or impressions, in order to free himself from painful complexes, by a process of "repression." Conversely in the mechanism of introversion, the personality tends to concentrate itself upon its complexes, and with them, to isolate itself from external reality, by a process which is not properly speaking "repression," but which would be better rendered perhaps by the term "depreciation" (Entwertung) of the objective world. The existence of two mental affections so opposite in character as hysteria and dementia præcox, in which the contrast rests on the almost exclusive supremacy of extroversion or introversion, suggests that these two psychological types may exist equally well in normal persons, who may be characterised by the relative predominance of one or other of the two mechanisms. Psychiatrists know very well that before either illness is fully declared, patients already present the characteristic type, traces of which are to be found from the earliest years of life. As Binet pointed out so well, the neurotic only accentuates and shews in relief the characteristic traits of his personality. One knows, of course, that the hysterical character is not simply the product of the illness, but pre-existed it in a measure. And Hoch has shown by his researches into the histories of his dementia præcox patients, that this is also the case with them; dissociations or eccentricities were present before the onset of the illness. If this is so, one may certainly expect to meet the same contrast between psychological temperaments outside the sphere of pathology. It is moreover easy to cull from literature numerous examples which bear witness to the actual existence of these two opposite types of mentality. Without pretending to exhaust the subject, I will give a few striking examples. In my opinion, we owe the best observations on this subject to the philosophy of William James.[185] He lays down the principle that no matter what may be the temperament of a "professional philosopher," it is this temperament which he feels himself forced to express and to justify in his philosophy. And starting from this idea, which is altogether in accord with the spirit of psychoanalysis, divides philosophers into two classes: the "tender-minded," who are only interested in the inner life and spiritual things; and the "tough-minded," who lay most stress on material things and objective reality. We see that these two classes are actuated by exactly opposite tendencies of the libido: the "tender-minded" represent introversion, the "tough-minded" extroversion.