Da Vinci's most well-known painting, and arguably the most famous painting in the world, the "Mona Lisa," was a privately commissioned work and was completed sometime between 1505 and 1507. Da Vinci has been called a genius and the archetypal Renaissance man. His talents inarguably extended far beyond his artistic works. Like many leaders of Renaissance humanism, he did not see a divide between science and art. His observations and inventions were recorded in 13,000 pages of notes and drawings, including designs for flying machines (some 400 years before the Wright brothers' first success), plant studies, war machinery, anatomy and architecture. His ideas were mainly theoretical explanations, laid out in exacting detail, but they were rarely experimental. His drawings of a fetus in utero, the heart and vascular system, sex organs, and other bone and muscular structures, are some of the first on human record.