" This led Montesquieu to become one of the earliest proponents of the trade theory of peace when he observed that hunting and herding nations often found themselves in conflict and wars, whereas trading nations “became reciprocally dependent,” making peace “the natural effect of trade.” The psychology behind the effect, Montesquieu speculated, was exposure of different societies to customs and manners different from their own, which leads to “a cure for the most destructive prejudices.” Thus, he concluded, “we see that in countries where the people move only by the spirit of commerce, they make a traffic of all the humane, all the moral virtues. "

― Michael Shermer , The Moral Arc: How Science and Reason Lead Humanity toward Truth, Justice, and Freedom