To some extent we can forgive sociology for this omission; indeed the estimation of mental elements in the science of society has hitherto been in fact a very trifling one. However, we cannot spare neurologists the reproach of having so long disregarded the pioneer researches of Breuer and Freud concerning the psychical determination of many nervous disturbances, and of having required the terrible experiences of the war to set them right in this respect. And yet a science—psycho-analysis—has existed for more than twenty years to which many investigators had devoted the whole of their efforts, and which had helped us to unexpected and important knowledge of the mechanisms of mental life and its disturbances. In my lecture today I shall confine myself to demonstrating the introduction of psycho-analysis into modern neurology, an introduction which has been effected to some small extent openly, but for the most part with hesitation and under false colours, and I will briefly communicate the theoretical principles upon which rest the psycho-analytical conceptions of the “traumatic neuroses” which have been observed during the war[1]. Soon after the outbreak of the war there flamed up again the great controversy, which had been carried on for more than ten years, concerning the nature of the traumatic neuroses which Oppenheim had in his time placed in a class by themselves. Oppenheim hastened to make use of the experiences of the war, which exposed so many thousands of men to sudden shocks, as supporting his old views, according to which the phenomena of these neuroses always came about, as the result of physical alterations in the nervous centres, (or in the peripheral nerves which secondarily affect those of the centre). The nature of the shock itself and its influence upon the method of functioning he described in very general, one might even say, phantastic terms. Links were “cut out” from the chain of the innervation mechanism, most delicate elements “displaced”, paths “blocked”, connections torn asunder, obstacles to conduction created, etc. With these and similar comparisons, from which, however, all basis in fact was tacking, Oppenheim sketched an impressive picture of the material correlation of the traumatic neuroses. The alterations in structure which would take place in the brain through the trauma Oppenheim conceived as a delicate physical process similar to that which occurs in the iron filing when it comes into contact with the magnet. The sarcastic Gaupp designates such specious physical and physiological speculations as brain mythology and molecular mythology. But in our opinion he does mythology an injustice.