&gt;  England will always be richer if it trades, no mater how good France is at manufacturing. That is the key insight.<p>Not what happened in real life.<p>Compare Argentina and USA. Both had been worse than Great Britain at industry, and better at agriculture. Argentina was more wealthy than USA at the start. Argentina have followed the theory (specializing in agriculture), USA acted on the contrary (introducing tariffs and specializing in industry).<p>At the end - USA is much more wealthy than Argentina.<p>Comparative advantage is about optimizing for current situation, not about strategic decisions.