Adam Smith came home to Kirkcaldy in the spring of 1767, at forty-three, having resigned a professorship at Glasgow to travel through France as tutor to a young duke. He had met Voltaire at Ferney and Quesnay and Turgot in Paris. He came back to a small port town with a life pension and a manuscript, and stayed roughly six years.⁴ The letters from those years are the letters of a man in difficulty.

Now we add a third layer: systems—the actual economic structures through which societies organize production and distribution. Understanding this distinction prevents the confusion that plagues contemporary political discourse, where “capitalism,” “socialism,” and “free markets” become tribal identifiers rather than analytical categories.