The Wealth of Nations by Part 4 Chapter 7 Page 63

own produce. The more, therefore, they pay for the one, the less they really get for the other, and the dearness of the one is the same thing with the cheapness of the other. The policy of Portugal is in this respect the same as the ancient policy of Spain with regard to all its colonies, except Fernambuco and Marannon, and with regard to these it has lately adopted a still worse.

Other nations leave the trade of their colonies free to all their subjects who may carry it on from all the different ports of the mother country, and who have occasion for no other licence than the common despatches of the custom-house. In this case the number and dispersed situation of the different traders renders it impossible for them to enter into any general combination, and their competition is sufficient to hinder them from making very exorbitant profits.