Which 20th century icon would you bring back to hear their thoughts?

Unfortunately, I'm horrible with names. There was a mathematician who went insane trying to find an equation for God. He got so close he could taste it, then it all went to hell.. No pun intended. I wish I could remember his name. Anywho, with the information of today and our reaches into therapy, I wonder how it could turn for him. Not just on that issue, but others.