A theory of international trade that originated with David Ricardo in the early 19th Century, and is maintained (in revised form) within neoclassical economics. The theory holds that a national economy will specialize through international trade in those products which it produces relatively most efficiently. Even if it produces those products less efficiently (in absolute terms) than its trading partner, it can still prosper through foreign trade. The theory depends on several strong assumptions – including an absence of international capital mobility, and a supply-constrained economy.