"There's a time when the operation of the machine becomes so odious, makes you so sick at heart, that you can't take part; you can't even passively take part, and you've got to put your bodies upon the gears and upon the wheels, upon the levers, upon all the apparatus, and you've got to make it stop."
Sketches of gears from Leonardo's notebooks. Did he know he was the first to design a mechanical calculator? Someone else is credited with it's invention around a 100 years later. His design/ invention was stowed away in his notebooks.