I’ve been thinking a bit lately about theories of the business cycle (a lot of time for reflection in these days of COVID-19). At least, I’ve been thinking of the way some of these theories have evolved over my lifetime and from the perspective of my own training in the field. From my (very narrow) perspective as a researcher and advisor at a central bank, the journey beginning c. 1960 seems like it’s taken the following steps: (1) Phillips Curve and some Natural Rate Hypothesis; (2) Real Business Cycle (RBC) theory; (3) New Keynesian theory. It seems like we might be ready to take the next step. I’ll offer some thoughts on this at the end, for whatever they’re worth.