"Colander: What’s your view of the New Keynesian approach? Tobin: I’m not sure what that means. If it means people like Greg Mankiw, I don’t regard them as Keynesians. I don’t think they have involuntary unemployment or absence of market clearing. It is a misnomer to call Mankiw any form of Keynesian. Colander: How about real-business-cycle theorists? Tobin: Well, that’s just the enemy."
January 1, 1970
https://en.wikiquote.org/wiki/Greg_Mankiw