On a larger scale, the Laffer curve may be the most important economic law of political history. Charles Adams uses it to explain the rise and fall of empires. Shelling Out (2002)
Barter works well at small volumes but becomes increasingly costly at large volumes, until it becomes too costly to be worth the effort. If there are n goods and services to be traded, a barter market requires n^2 prices. Shelling Out (2002)