 In his Second Treatise of Government, Locke famously stated that “labor fixes property.” It is the labor of people in the fields of philosophy that fixes a philosophical text as a “property”—that marks its bounds and assesses its value. But a work that has remained outside contemporary philosophy’s pedagogical economy, as has Hartley’s Observations, is in an indeterminate position. A person today who picks the book up would have in hand a long book covering a multitude of topics. How to determine its properties? And how to answer the question of economics: What is its worth? To address these questions, let us imagine how one of Hartley’s colleagues, a Fellow of the Royal Society (FRS), might have responded to the book on its appearance in 1749.