The main goal of this article is to identify and critically examine the foundations of the monetary theories to which Lowndes and Locke appealed during their debate around the Great Recoinage of 1696. In the course of the investigation I came by the critical commentaries of Sir James Steuart and Karl Marx on the views of Locke and Lowndes on monetary theory. As these highly valuable commentaries are nearly absent from the standard literature, I present and critically assess them in this essay.