… is from David Hume’s essay, first published in 1759 or 1760, “Of the Jealousy of Trade” (here from pages 327-328 of the 1985 Liberty Fund collection of some of Hume’s essays, edited by the late Eugene F. Miller, Essays: Moral, Political, and Literary):
Nothing is more usual, among states which have made some advances in commerce, than to look on the progress of their neighbours with a suspicious eye, to consider all trading states as their rivals, and to suppose that it is impossible for any of them to flourish, but at their expence. In opposition to this narrow and malignant opinion, I will venture to assert, that the encrease of riches and commerce in any one nation, instead of hurting, commonly promotes the riches and commerce of all its neighbours; and that a state can scarcely carry its trade and industry very far, where all the surrounding states are buried in ignorance, sloth, and barbarism.
It is obvious, that the domestic industry of a people cannot be hurt by the greatest prosperity of their neighbours; and as this branch of commerce is undoubtedly the most important in any extensive kingdom, we are so far removed from all reason of jealousy. But I go farther, and observe, that where an open communication is preserved among nations, it is impossible but the domestic industry of every one must receive an encrease from the improvements of the others.