Tom Sargent on why he joined NYU:

”I need other people to do my best work. Economics is like sports — the real stuff is being done by young guys, and you have to work hard to keep up with them. Old guys like me are like boxers — we’ve seen a lot of moves, but our reflexes are slower. There are a lot of young guys here to keep me sharp.”

To add to this: when someone comes up with some supposedly “new” moves, old guys can tell whether they are reinventing the wheel or whether it is a really new move.  Zvi Griliches used to play this role at Harvard.  Does this knowledge help you to come up with some really new moves yourself?  I’m not sure.