Leonardo's views of aesthetic are all important in his philosophy of life and art. The worker's thoughts on his craft are always of interest. They are doubly so when there is in them no trace of literary self-consciousness to blemish their expression. He recorded these thoughts at the instant of their birth, for a constant habit of observation and analysis had early developed with him into a second nature. His ideas were penned in the same fragmentary way as they presented themselves to his mind, perhaps with no intention of publishing them to the world. But his ideal of art depended intimately, none the less, on the system he had thrown out seemingly in so haphazard a manner.