MacEwan finds the essence of neoliberalism to be the doctrine that economic growth is maximized when movements of goods, services and capital, but not labour, are unimpeded by governmental regulations. MacEwan traces this position to the Ricardian notion that countries gain (i.e. have growing economies) by specializing on goods for which they have the greatest comparative advantage (as with Britain producing cloth and Portugal wine in the eighteenth century), or least comparative disadvantage and trading these goods freely. This static theory of trade was made into a dynamic growth model by adding a sequence of further arguments. Economies growing through trade have higher levels of savings and, when turned into investments, these increase productivity.