the course of their sexual investigation children feel that the grown up knows something wonderful in the mysterious and yet so important realm, what they are prohibited from knowing or doing, they are seized with a violent wish to know it, and dream of it in the form of flying, or prepare this disguise of the wish for their later flying dreams. Thus aviation, which has attained its aim in our times, has also its infantile erotic roots.
By admitting that he entertained a special personal relation to the problem of flying since his childhood, Leonardo bears out what we must assume from our investigation of children of our times, namely, that his childhood investigation was directed to sexual matters. At least this one problem escaped the repression which has later estranged him from sexuality. From childhood until the age of perfect intellectual maturity this subject, slightly varied, continued to hold his interest, and it is quite possible that he was as little successful in his cherished art in the primary sexual sense as in his desires for mechanical matters, that both wishes were denied to him.
