Where Adam Smith and David Ricardo had envisaged a growing worldwide division of labor, they had thought that each country would freely select the commodities it was most qualified to produce, and that each would exchange its optimal commodity for the optimal commodity of others. Thus in Ricardo's example, Britain would send Portugal its textiles, while Britons would consume Portuguese wines in turn. What his vision of free commodity exchange omits are the constraints that governed the selection of particular commodities, and the political and military sanctions used to ensure the continuation of quiet asymmetrical exchanges that benefited one party while diminishing the assets of another.