Smartest man in history? Eh? What do ya think? Just a reminder, this is obviously impossible to come up with a definite answer, should probally be based off of acions they made in their life. Time period should also be taken into account, I mean it doesn't matter how much more intelligent archimedes is to Edison, considering the technology and company of the time Archimedes would have never been able to create an effective incandescent lightbulb. My vote is for Leonardo Da Vinci. This guy was a skilled scientist, mathematician, engineer, inventor, anatomist, painter, sculptor, architect, botanist, musician, poet and writer.