This essay tries to synthesise the rise of demand-boosting fiscal policy as one of the hottest topic in contemporary macroeconomics. In some sense, the analysis and debate about fiscal policy never went away, but it is fair to say that ideas which were previously thought buried have recently risen, and appear stronger than ever. The essay starts with the core ides presented by John Maynard Keynes, and how Keynesianism flourished and eventually died, before now rising again in the context of the hottest theory in town; modern monetary theory or MMT. This essay can be read with advantage in conjunction with one of my recent blog posts; Woke Economics. The first edition of this essay was published in 2020. Newer editions might follow and will be available here.