Markets Shape What Work We Can Do — The Wealth of Nations

Smith's main rule here is simple: you can only specialize as far as you can sell. A market town may support a porter. A tiny Scottish village cannot. Out there each farmer must act as butcher, baker, and brewer for his own family. A skilled nail maker in that place could make a year's supply in one day and have nowhere to sell the extras.

Cheap transport widens markets. Smith compares a wagon and a ship moving goods between London and Edinburgh. A few men with a ship can move what dozens of wagons and hundreds of horses struggle to carry. So industry first booms along coasts and rivers, and only later spreads inland. North American plantations followed the same pattern along navigable water.

He looks at history. Egypt, Bengal, and parts of China grew early partly because rivers linked towns. London and Calcutta trade today because sea routes make huge markets possible. Cut people off from buyers, and they must go back to doing everything themselves.

The lesson is practical. Roads, ports, cities, and trade rules decide how deep specialization can go. When markets stay small, people remain jacks-of-all-trades whether they want to or not. Smith ends by setting up the next problem: once wide markets exist, direct barter itself becomes the bottleneck.