Regular, periodic taxation is a function of modern government, a practice that arose only because the rent of land and natural resources was transformed from the traditional source of public revenue in the Middle Ages to private property, starting in the 17th century. In the earlier era, taxes (special exactions on ordinary income and daily necessities) were imposed only under unusual circumstances, usually to fight wars. The French Physiocrats and their student, Adam Smith, proposed that the best form of modern taxation would be based on the same principle as the medieval system—a fee derived entirely from surpluses, not imposed as a burden on production. This was actually what Adam Smith meant by “ability to pay.” Smith's sophisticated understanding of economic rent was, however, simplified and distorted by numerous economists throughout the 19th century, who buried the concept under layers of obfuscation. In particular, the substitution of “Paretian rent” for “Ricardian rent” committed the fallacy of composition by shifting rent from a social concept to a private, unit‐level concept, which caused social surplus to simply “disappear.” Bringing this “lost history” to light permits us to re‐evaluate how modern societies might benefit from Smith's physiocratic concept of taxation. This work not only traces debates about rent—for example, whether rent arises from risk‐taking, or whether a tax on rent raises commodity prices—but also discusses the practical benefits of taxing it today.