Although commerce is subject to great transformations, it can happen that certain physical causes, and the quality of the terrain or of the climate, fix its nature forever.
We trade today with the Indies only by means of the silver we send there. The Romans  took about fifty million sestertii there every year. That silver, like ours today, was converted into merchandise which they brought back to the west. All the peoples who have traded in the Indies have always borne metals thence and returned with merchandise.
It is nature herself that produces this effect. The Indians have their arts, which are adapted to their manner of living. Our luxury cannot be theirs, nor our needs their needs. Their climate requires of them or allows them almost nothing that comes from us. They largely go naked ; the clothing they have is suitable as it is furnished them by the country ; and their religion, which is indestructible, makes repugnant to them the kind of things that are food to us. The only thing they need therefore is our metals, which are signs of value, in exchange for which they give merchandise, which their frugality and the nature of their country provides them in great abundance. The ancient writers who have spoken to us of the Indies depict them as we see them today, so far as public order, manners, and ways are concerned.  The Indies have been, and the Indies will be, what they are at present ; and in all times those who deal in the Indies will bear silver thence and bring none back.