But whatever may be the truth about Leonardo's life we cannot relinquish our effort to investigate it psychoanalytically before we have finished another task. In general we must mark out the limits which are set up for the working capacity of psychoanalysis in biography so that every omitted explanation should not be held up to us as a failure. Psychoanalytic investigation has at its disposal the data of the history of the person's life, which on the one hand consists of accidental events and environmental influences, and on the other hand of the reported reactions of the individual. Based on the knowledge of psychic mechanisms it now seeks to investigate dynamically the character of the individual from his reactions, and to lay bare his earliest psychic motive forces as well as their later transformations and developments. If this succeeds then the reaction of the personality is explained through the coöperation of constitutional and accidental factors or through inner and outer forces. If such an undertaking, as perhaps in the case of Leonardo, does not yield definite results then the blame for it is not to be laid to the faulty or inadequate psychoanalytic method, but to the vague and fragmentary material left by tradition about this person. It is, therefore, only the author who forced psychoanalysis to furnish an expert opinion on such insufficient material, who is to be held responsible for the failure. However, even if one had at his disposal a very rich historical material and could manage the psychic mechanism with the greatest certainty, a psychoanalytic investigation could not possibly furnish the definite view, if it concerns two important questions, that the individual could turn out only so and not differently. Concerning Leonardo we had to represent the view that the accident of his illegitimate birth and the pampering of his mother exerted the most decisive influence on his character formation and his later fate, through the fact that the sexual repression following this infantile phase caused him to sublimate his libido into a thirst after knowledge, and thus determined his sexual inactivity for his entire later life. The repression, however, which followed the first erotic gratification of childhood did not have to take place, in another individual it would perhaps not have taken place or it would have turned out not nearly as profuse. We must recognize here a degree of freedom which can no longer be solved psychoanalytically. One is as little justified in representing the issue of this shift of repression as the only possible issue. It is quite probable that another person would not have succeeded in withdrawing the main part of his libido from the repression through sublimation into a desire for knowledge; under the same influences as Leonardo another person might have sustained a permanent injury to his intellectual work or an uncontrollable disposition to compulsion neurosis. The two