1) The comparative cost advantage theory originated from works by Robert Torrens, David Ricardo, James Mill, and John Stuart Mill in the early 19th century. 2) According to Ricardo's law of comparative advantage, even if one country is more efficient than another in producing every good, both countries can still benefit from trade. A country should specialize in the goods where they have the lowest relative production costs. 3) The assumptions of the comparative cost advantage theory include two countries and commodities, perfect competition, labor as the only factor of production, and free international trade. Gains from trade occur when countries specialize according to their comparative advantages.