Most international trade has always taken place by sea, so if North America’s geography favors agriculture, then England’s favors trade. But these geographical factors don’t explain different countries’ development patterns on their own. Rather, as Smith showed throughout Book III, political institutions must incentivize the right kind of economic activity. These institutions must protect people’s economic rights, so that they feel secure investing capital in land or business over the long term. And these institutions must also do their best to encourage the right kinds of investment, while fighting monopolies. After all, for Smith, there is no hard-and-fast distinction between politics and economics; there is just political economy. Book IV will explore all of these issues in much more depth. In particular, it will show how different nations’ economic policies have combined with their particular histories and geography to shape their economic outcomes.