remember Da Vinci was into a lot of things, including anatomy and made quite some discoveries in that field as well. Quoting http://www.discoveringdavinci.com/s

remember Da Vinci was into a lot of things, including anatomy and made quite some discoveries in that field as well. Quoting http://www.discoveringdavinci.com/sex-uality/ http://www.discoveringdavinci.com/sex-uality/ (which is a great site BTW): "Leonardo was the first to realize the function of the pubic bone. Before da Vinci people believed that the penis was erected by “magic air” he realized that it was actually filled with blood. He also was probably the first to document erectile malfunction and said that penises seems to have a mind of their own."