During my visit to Venice I found a museum with interactive exhibits by Leonardo da Vinci. It's actually hard to appreciate full scale of his genius unless you

During my visit to Venice I found a museum with interactive exhibits by Leonardo da Vinci. It's actually hard to appreciate full scale of his genius unless you actually try out each of the devices he created by your own hand. Most of these devices are very minimal and simple, something even you could build in half a day with right tools, but just magical. Even more importantly, what I learned was that he didn't just pulled them out his brilliant brain in one stroke. He meticulously studied how extremely simple things like gears, pulleys, levers, wheels & axle, inclined planes, friction, and screws behave and why do they behave that way. Then he started studying how lot of medieval machines that were already in existence simply be viewed as composition of these simple elements. Then he studied newer ways to compose them to build ever more complicated machines. So after years of such studies he was able to create these magical devices which worked without electricity, steam and such way back in 1500s. One of the device on display was ball bearings he had made and he was generally attributed as his inventor.