"As a young man, Leonardo was exceptionally beautiful. ... He was a homosexual vegetarian born out of wedlock who received very little formal education and was excluded by birthright from almost all professions. He was a mass of contradictions and conflicts, a man who rarely completed a commission ... [but wanted to] do as much as he possibly could and record everything he witnessed.
He wrote disapprovingly of war, but designed military hardware for several different European warlords; he was a masterful painter, perhaps the greatest who ever lived, but tired of art. He was scornful of received wisdom but steeped himself in classical learning, and while he believed the human form was the ultimate expression of the divine, he despised humanity. ... "
Leonardo was never able to come fully to terms with the fact that he had been deprived of a formal university education. ...
He once wrote with barely disguised bitterness: '[Establishment scholars] strut about puffed up and pompous, decked out and adorned not with their own labours but with those of others and they will not even allow me my own.' ..."
At other times he displayed what some may consider to be an unhealthy contempt for humans in general, once declaring: 'How many people there are who could be described as mere channels for food, producers of excrement, fillers of latrines, for they have no other purpose in this world; they practise no virtue whatsoever; all that remains after them is a full latrine.' "Michael White, Leonardo, The First Scientist, St. Martin's Press, 2000, pp. 7-19.