There may be some of you who perhaps are friendly enough towards psycho-analysis, often attacked as it is, to wish that it would justify itself in another direction also, that is, therapeutically. You know that psychiatric therapy has hitherto been unable to influence delusions. Can psycho-analysis do so perhaps, by reason of its insight into the mechanism of these symptoms? No, I have to tell you that it cannot; for the present, at any rate, it is just as powerless as any other therapy to heal these sufferers. It is true that we can understand what has happened to the patient; but we have no means by which we can make him understand it himself. You have heard that I could not continue the analysis of this delusion beyond the first preliminaries. Would you then maintain that analysis of such cases is undesirable because it remains fruitless? I do not think so. It is our right, yes, and our duty, to pursue our researches without respect to the immediate gain effected. The day will come, where and when we know not, when every little piece of knowledge will be converted into power, and into therapeutic power. Even if psycho-analysis showed itself as unsuccessful with all other forms of nervous and mental diseases as with delusions, it would still remain justified as an irreplaceable instrument of scientific research. It is true that we should not be in a position to practise it; the human material on which we learn lives, and has its own will, and must have its own motives in order to participate in the work; and it would then refuse to do so. I will therefore close my lecture for to-day by telling you that there are large groups of nervous disturbances for which this conversion of our own advance in knowledge into therapeutic power has actually been carried out; and that with these diseases, otherwise so refractory, our measures yield, under certain conditions, results which give place to none in the domain of medical therapy. SEVENTEENTH LECTURE THE MEANING OF SYMPTOMS