Not much there

Keynesian analysis as I define it implies that you need monetary policy, and occasionally countercyclical fiscal policy, to stabilise the economy, but that is not what is generally meant by a mixed economy! Simon Lewis

There is an ongoing debate about schools of though in economics. What is Keynesianism? It is not as vague as the definition above. I can substitute, oil, housing, roads, clean air, and shoe laces:

Keynesian analysis as I define it implies that you need shoelace policy, and occasionally countercyclical shoe policy, to stabilize the economy Me

I used to use the shoelace metaphor a lot, then one day I looked it up. Something like 30,000 serious injuries a year happen from untied or broken shoelaces.

But the point is, saying that the waves must go up and down does not define a theory. Your theory is defined by the units of measure your normative agent executes.