The lever is the greatest discovery of all. Not the wheel, nor the bigger wheel.
I'd hate to be pedantic but the lever may have been the greatest
'discovery of all' but is it really an 'invention' ?
Any Tom Dick or Harry (or Issac Newton in the case of gravity) can come along and 'discover' something, it take's real genius to actually 'invent' something like a wheel, big wheel or sliced bread ?
For example, most people on here have 'discovered' that Altrincham FC are the best football team since sliced bread, but the guy who invented them ? Well that was pure genius ? (and depending when sliced bread was invented, may have even been before sliced bread was invented ?) - Now that is a true genius ?
I rest my case !