In these lectures I have attempted to reconcile my practical experiences in psychoanalysis with the existing theory, or rather, with the approaches to such a theory. Here is my attitude towards those principles which my honored teacher Sigmund Freud has evolved from the experience of many decades. Since I have long been closely connected with psychoanalysis, it will perhaps be asked with astonishment how it is that I am now for the first time defining my theoretical position. When, some ten years ago, it came home to me what a vast distance Freud had already travelled beyond the bounds of contemporary knowledge of psycho-pathological phenomena, especially the psychology of the complex mental processes, I no longer felt myself in a position to exercise any real criticism. I did not possess the sorry mandarin-courage of those people who—upon a basis of ignorance and incapacity—consider themselves justified in “critical” rejections. I thought one must first work modestly for years in such a field before one might dare to criticize. The evil results of premature and superficial criticism have certainly not been lacking. A preponderating number of critics have attacked with as much anger as ignorance. Psychoanalysis has flourished undisturbed and has not troubled itself one jot or tittle about the unscientific chatter that has buzzed around it. As everyone knows, this tree has waxed mightily, and not in one world only, but alike in Europe and in America. Official criticism participates in the pitiable fate of Proktophantasmist and his lamentation in the Walpurgis-night: “You still are here? Nay, ’tis a thing unheard! Vanish at once! We’ve said the enlightening word.” Such criticism has omitted to take to heart the truth that all that exists has sufficient right to its existence: no less is it with psychoanalysis. We will not fall into the error of our opponents, nor ignore their existence nor deny their right to exist. But then this enjoins upon ourselves the duty of applying a proper criticism, grounded upon a practical knowledge of the facts. To me it seems that psychoanalysis stands in need of this weighing-up from the inside. It has been wrongly assumed that my attitude denotes a “split” in the psychoanalytic movement. Such a schism can only exist where faith is concerned. But psychoanalysis deals with knowledge and its ever-changing formulations. I have taken William James’ pragmatic rule as a plumb-line: “You must bring out of each word its practical cash-value, set it at work within the stream of your experience. It appears less a solution, then, than as a program for more work and more particularly as an indication of the ways in which existing realities may be changed. _Theories thus become instruments, not answers to enigmas, in which we can rest._ We don’t lie back upon them, we move forward, and, on occasion, make nature over again by their aid.”