“The sketches and text show Leonardo understood the fundamentals of friction in 1493,” says Hutchings. “He knew that the force of friction acting between two sliding surfaces is proportional to the load pressing the surfaces together and that friction is independent of the apparent area of contact between the two surfaces. These are the ‘laws of friction’ that we nowadays usually credit to a French scientist, Guillaume Amontons, working 200 years later.”
It is an unfortunately thing that da Vinci lived and worked in Italy. Though this was where the Renaissance blossomed, it is also the place where some scientists at the time were persecuted for being too honest about their research. To protect himself da Vinci confined his scientific genius to his private diaries, written in a backwards script he created so that no one could easily understand them. Thus, while his brilliance as a painter was recognized in his lifetime and after, the discoveries he had made about engineering and science were lost for literally centuries.