Leonardo was called die Italian Faust on account of his insatiable and indefatigable desire for investigation. But even if we disregard the fact diat it is the possible retransformation of the desire for investigation into the joys of life which is presupposed in the Faust tragedy, one might venture to remark diat Leonardo's system recalls Spinoza's mode of thinking.

The transformation of psychic motive power into the different forms of activity is perhaps as little convertible without loss, as in the case of physical powers. Leonardo's example teaches how many other tilings one must follow up in these processes. Not to love before one gains full knowiedge of the tiling loved presupposes a delay which is harmful. When one finally reaches cognition one neither loves nor hates properly; one remains beyond love and hatred. One has investigated instead of having loved. It is perhaps for diis reason that Leonardo's life was so much poorer in love than those of other great men and great artists. The storming passions of the soul-stirring and consuming kind, in which odiers experience the best part of dieir lives, seem to have missed him.

There are still other consequences when one follows Leonardo's dictum. Instead of acting and producing one just investigates. He who begins to divine the grandeur of the universe and its needs readily forgets his own insignificant self. When one is struck widi admiration and becomes truly humble one easily forgets that one is a part of that living force, and diat according to the measure of one's own personality one has die right to make an effort to change diat destined course of the world, the world in which the insignificant is no less wonderful and important than the great.

Solmi thinks that Leonardo's investigations started with his art,²³ that he tried to investigate the attributes and laws of light, of color, of shades and of perspective so as to be sure of becoming a master in the imitation of nature and to be able to show the way to others. It is probable diat already at diat time he overestimated the value of diis knowledge for the artist. Following the guide-rope of the painter's need, he was then driven furdier and further to investigate the objects of the art of painting, such as animals and plants, and the proportions of die human body, and to follow the padi from their exterior to their interior structure and biological functions, which really also express themselves in their appearance and should be depicted in art. And finally he was pulled along by this overwhelming desire until the connection was torn from the demands of his art, so that he discovered the general laws of mechanics and divined the history of the stratification and fossilization of the Arno-valley, until he could enter in his book with capital letters the cognition: II sole non si move (The sun does not move). His investigations were thus extended over almost all realms of natural science, in every one of which he was a discoverer or at least a prophet or forerunner.²¹ However, his curiosity continued to be directed to the outer world, something kept him away from die investigation of the psychic life of men; there was little room for psychology in the "Academia Vinciana, " for which he drew very artistic and very complicated emblems.

When he later made the effort to return from his investigations to the art from which he started he felt that he was disturbed by die new paths of his interest and by die changed nature of his psychic work. In the picture he was interested above all in a problem, and behind this one he saw emerging numerous other problems just as he was accustomed in the endless and indeterminable investigations of natural history. He was no longer able to limit his demands, to isolate die work of art, and to tear it out from that great connection of which he knew it formed part. After the most exhausting efforts to bring to expression all that was in him, all that was connected with it in his thoughts, he was forced to leave it unfinished, or to declare it incomplete.

The artist had once taken into his service the investigator to assist him, now the servant was stronger and suppressed his master.

When we find in the portrait of a person one single impulse very forcibly developed, as curiosity in the case of Leonardo, we look for die explanation in a special constitution. Concerning its probable organic determination hardly anything is known. Our psychoanalytic studies of disturbed people lead us to look for two odier expectations which we would like to find verified in every case. We consider it probable that this very forcible impulse was already active in die earliest childhood of die person, and diat its supreme sway was fixed by infantile impressions; and we furtiier assume that originally it drew upon sexual motive powers for its reeiiforcement so that it later can take the place of a part of the sexual life. Such a person would then, e.g., investigate with that passionate devotion which another would give to his love, and he could investigate instead of loving. We would venture the conclusion of a sexual reinforcement not only in the impulse to investigate, but also in most other cases of special intensity of an impulse.

Observation of daily life shows us that most persons have the capacity to direct a very tangible part of dieir sexual motive powers to their professional or business activities. The sexual impulse is particularly suited to yield such contributions because it is endowed with the capacity of sublimation, i.e., it has the power to exchange its nearest aim for others of higher value which are not sexual. We consider diis process as proved, if die history of childhood or the psychic developmental history of a person shows that in childhood diis powerful impulse was in the service of the sexual interest. We consider it a further corroboration if this is substantiated by a striking stunting in die sexual life of mature years, as if a part of die sexual activity had now been replaced by the activity of die predominant impulse.