A cornerstone of Keynesian economic theory is that the prosperity of the nation depends heavily on the amount that the state expends on the general welfare and on public works in particular. This paper will consider historiographical arguments around the application of this theory to Classical Athens of the 5th-4th c. BC. This example has been used to illustrate how, at times in which public outlays were high, the state also experienced significant prosperity, even reaching the apex of its power and dominance. And, conversely, when the amount of money expended by the state shrank and wealth was concentrated in fewer hands, it suffered diminished status. This amounts to a retrospective application of Keynesian economics that will, hopefully, illustrate a key fact of economic practice devoid, as far as possible, from the overarching ideologies that affect such theories in modernity. This is not an uncontroversial approach and the aim of this article is to examine previous attempts to apply this theory along with the criticisms of them.