Joseph Schumpeter famously claimed that the economic theories of French Enlightenment thinker François Quesnay contained “the first method ever devised in order to convey an explicit conception of the nature of economic equilibrium.” In this chapter, Jacobsen interprets Quesnay’s innovations and supporting arguments in the context of the conceptual and metaphysical underpinnings that where at play more generally for Quesnay and his group of Physiocrats. The chapter claims that the strong Physiocratic rhetoric of an essential connection between economic equilibrium, epistemological certainty and political necessity became a decisive moment in the development of economic thought. The Physiocratic ideas of macroeconomic flows of capital were quickly abandoned, but their idea of a nexus between equilibrium and necessity became a lasting normative framework for later economic thinking.