The application of diese assumptions to the case of the predominant investigation-impulse seems to be subject to special difficulties, as one is unwilling to admit that this serious impulse exists in children or that children show any noteworthy sexual interest. However, these difficulties are easily obviated. The untiring pleasure in questioning as seen in little children demonstrates their curiosity, which is puzzling to die grown-up, as long as he does not understand that all these questions are only circumlocutions, and diat they cannot come to an end because they replace only one question which the child does not put. When the child becomes older and gains more understanding this manifestation of curiosity suddenly disappears. But psychoanalytic investigation gives us a full explanation in that it teaches us that many, perhaps most children, at least die most gifted ones, go through a period beginning widi die third year, which may be designated as the period of infantile sexual investigation. As far as we know, die curiosity is not awakened spontaneously in children of this age, but is aroused through die impression of an important experience, through the birth of a little brodier or sister, or through fear of the same endangered by some outward experience, wherein the child sees a danger to his egotistic interests. The investigation directs itself to the question whence children come, as if the child were looking for means to guard against such an undesired event. We were astonished to find that the child refuses to give credence to the information imparted to it, e.g., it energetically rejects the mythological and ingenious stork-fable. We were astonished to find that its psychic independence dates from this act of disbelief, that it often feels itself at serious variance with the grown-ups, and never forgives them for having been deceived about the truth on this occasion. It investigates in its own way, it divines that the child is in the mother's womb, and guided by die feelings of its own sexuality, it formulates for itself theories about the origin of children from food, about being born dirough the bowels, about the role of die father which is difficult to fathom, and even at that time it has a vague conception of the sexual act which appears to the child as something hostile, as something violent. But as its own sexual constitution is not yet equal to the task of producing children, its investigation whence come children must also run aground and must be left in the lurch as unfinished. The impression of this failure at the first attempt of intellectual independence seems to be of a persevering and profoundly depressing nature.2'

If the period of infantile sexual investigation comes to an end dirough an impetus of energetic sexual repression, die early association with sexual interest may result in diree different possibilities for the future fate of the investigation impulse. The investigation either shares the fate of the sexuality, the curiosity henceforth remains inhibited and the free activity of intelligence may become narrowed for life; diis is especially made possible by the powerful religious inhibition of thought, which is brought about shortly hereafter through education. This is the type of neurotic inhibition. We know well that such acquired mental weakness furnishes effective support for the outbreak of a neurotic disease. In a second type the intellectual development is sufficiently strong to withstand the sexual repression pulling at it. Sometimes after the disappearance of the infantile sexual investigation, it offers its support to the old association in order to elude die sexual repression, and die suppressed sexual investigation comes back from the unconscious as compulsive reasoning, naturally distorted and not free, but forceful enough to sexualize even thought itself and to accentuate die intellectual operations with the pleasure and fear of die actual sexual processes. Here die investigation becomes sexual activity and often exclusively so, the feeling of settling the problem and of explaining things in the mind is put in place of sexual gratification. But the indeterminate character of the infantile investigation also repeats itself in the fact that this reasoning never ends, and that the desired intellectual feeling of the solution constantly recedes into the distance. By virtue of a special disposition the third, which is the most rare and most perfect type, escapes the inhibition of thought and die compulsive reasoning. Here also sexual repression takes place. It is unable, however, to direct a partial impulse of the sexual pleasure into the unconscious. The libido withdraws from the fate of the repression by being sublimated from the beginning into curiosity, and by reenforcing the powerful investigation impulse. Here, too, the investigation becomes more or less compulsive and a substitute of the sexual activity, but owing to the absolute difference of the psychic process behind it (sublimation in place of the emergence from the unconscious) the character of the neurosis does not manifest itself, the subjection to the original complexes of the infantile sexual investigation disappears, and the impulse can freely put itself in the service of the intellectual interest. It takes account of the sexual repression which made it so strong by contributing sublimated libido to it, by avoiding preoccupation widi sexual themes.

In mentioning the concurrence in Leonardo of the powerful investigation impulse widi the stunting of his sexual life, which was limited to so-called ideal homosexuality, we feel in-dined to consider him as a model example of our diird type. The most essential point of his character and the secret of it seems to lie in the fact that after utilizing the infantile activity of curiosity in the service of sexual interest he was able to sublimate the greater part of his libido into the impulse of investigation. But, to be sure, die proof of this conception is not easy to produce. To do this we would have to have an insight into die psychic development of his first childhood years, and it seems foolish to hope for such material when the reports concerning his life are so meager and so uncertain; and moreover, when we deal widi information which even persons of our own generation withdraw from the attention of the observer.

We know very little concerning Leonardo's youth. He was born in 1452 in the little city of Vinci between Florence and Empoli; he was an illegitimate child, which was surely not considered a great popular stain in that time. His father was Ser Piero da Vinci, a notary and descendant of notaries and farmers, who took their name from the place Vinci. His mother was a certain Caterina, probably a peasant girl, who later married another native of Vinci. Nothing else about his mother appears in the life history of Leonardo, only die poet Merejkowski believed he had found some traces of her. The only definite information about Leonardo's childhood is furnished by a legal document from die year 1457, a register of assessment in which Vinci Leonardo is mentioned among die members of the family as a five-year-old illegitimate child of Ser Piero.2' As the marriage of Ser Piero with Donna Albiera remained childless the little Leonardo could be brought up in his fadier's house. He did not leave diis house until he entered as apprentice —it is not known what year—die studio of Andrea del Verrocchio. In 1472 Leonardo's name could already be found in die register of die members of the "Compagnia dei Pittori." That is all.