The document discusses several theories of international trade:
1. Mercantilism held that a nation's wealth depended on accumulating gold and silver through trade surpluses. It advocated subsidies for exports and tariffs/quotas on imports.
2. Adam Smith's absolute advantage theory argued that countries should specialize in goods they produce most efficiently and trade for other goods. Both countries can benefit through specialization and trade.
3. David Ricardo's comparative advantage theory extended this, showing that trade can benefit both sides even if one country is more efficient overall. Countries should import goods they have a comparative - not absolute - disadvantage in.
4. Later theories examined factors like differences in factor endowments