I'd say Keynesianism can be summed up by his famous statement, "In the long run we are all dead." It's the acknowledgement that simplistic macroeconomic models

I'd say Keynesianism can be summed up by his famous statement, "In the long run we are all dead." It's the acknowledgement that simplistic macroeconomic models may describe asymptotic behavior, but while the dynamic system is slowly trending to those ends, many people can suffer. Thus, in the meantime, it'd be good to have some market intervention. Intervention in moderation, for moderation.