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Excerpt from Mill's Principles of Political Economy

"But the economical advantages of commerce are surpassed in importance by those of its effects which are intellectual and moral. It is hardly possible to overrate the value, in the present low state of human improvement, of placing human beings in contact with persons dissimilar to themselves, and with modes of thought and action unlike those with which they are familiar. Commerce is now what war once was, the principal source of this contact. Commercial adventurers from more advanced countries have generally been the first civilizers of barbarians. And commerce is the purpose of the far greater part of the communication which takes place between civilized nations. Such communication has always been, and is peculiarly in the present age, one of the primary sources of progress. To human beings, who, as hitherto educated, can scarcely cultivate even a good quality without running it into a fault, it is indispensable to be perpetually comparing their own notions and customs with the experience and example of persons in different circumstances from themselves: and there is no nation which does not need to borrow from others, not merely particular arts or practices, but essential points of character in which its own type is inferior. Finally, commerce first taught nations to see with good will the wealth and prosperity of one another. Before, the patriot, unless sufficiently advanced in culture to feel the world his country, wished all countries weak, poor, and ill-governed, but his own: he now sees in their wealth and progress a direct source of wealth and progress to his own country. It is commerce which is rapidly rendering war obsolete, by strengthening and multiplying the personal interests which are in natural opposition to it. And it may be said without exaggeration that the great extent and rapid increase of international trade, in being the principal guarantee of the peace of the world, is the great permanent security for the uninterrupted progress of the ideas, the institutions, and the character of the human race."