 Quesnay’s model made stylized assumptions about the French nation, ascribing three distinct classes: a quarter were landowners (aristocrats), a quarter artisans, and half farmers. He showed visually that after the initial payment of rent (the annual net product) by the farmers to the landowners, the entire unfolding of the economy would reach mathematical closure by the time of the next harvest and, like a perpetual motion machine, prompt the next period of production and distribution. No sector would increase or decrease in size and each would have its just reward in accordance with its station (a stylized assumption was that landowners consumed twice as much as the others, per capita). Quesnay also, brilliantly, introduced disturbances, for example, an unduly high interest rate, a tax, or an increased demand for artisanal goods, to demonstrate the rapid disequilibration of his system (see Quesnay 1758-1759). Contemporary modelling thrives on introducing slight variations or manipulations to disclose the underlying structure and is much indebted to Quesnay (see Hausman 2003 [2021]; Morgan 2012).