By the 1890s, the United States had consolidated its continental empire and was beginning to redefine its relations with the rest of the world. America was now a very large, unified nation. Its population had grown by more than 25 percent in the previous decade, and the great tide of immigrants was still flowing across the Atlantic. Having just become the world's leading industrial producer, the United States was tempted to flex its new economic muscles and maybe even assert its power abroad. Maybe even among the developed nations of Europe.

It was not at all clear, however, what the United States would do or should do. It was unclear to most Americans that it was wise to intrude on the affairs of other powerful nations. George Washington's famous Farewell Address had established the central principle that had guided American foreign policy in the nineteenth century. Over two centuries later, it's still worth quoting.