… is from page 48 of the original edition of Lee Francis Lybarger’s 1914 book, The Tariff  (original emphasis):
The Tariff is one of the greatest obstacles all over the earth today to international peace. From its very nature it tends to emphasize political boundaries and to perpetuate national and race hatreds. The arguments in its behalf must constantly make a wide distinction between home goods and foreign goods. This of necessity tends to perpetuate and intensify the association of “foreigner” with “foe.”
DBx: Commerce civilizes. Commerce also, in part by making war even more absurd and destructive than it naturally is, pacifies . Nationalism, to the extent that it artificially obstructs commerce that crosses political borders, works counter to commerce’s civilizing and pacifying consequences.
It might be that, as a practical matter, the nation-state is here to stay, at least for the foreseeable future. It might also be – and also as a practical matter – that the nation-state is the least-imperfect of all feasible political arrangements today, given human nature and current expectations, and given also current conceptions of political realities and possibilities. But the validity of these “it-might-bes” ought not blind us to the always enormous, and often sanguinary, danger lurking within nationalism.
Nationalism too blithely embraced – which it is too often – confuses the individual with some group, and leads quickly to the sense that the individual is subordinate to the group of which nationalist ideology proclaims him or her to be a part. Nationalism – as is true of all forms of collectivism – blinds those who embrace it to the emergent orders that arise from individual choices and actions.
This latter blindness isn’t an inevitable logical consequence of nationalism, but I believe it to be a highly prevalent psychological consequence. The relevant actor, in the nationalist’s mind, is the nation – or, more precisely, the nation as represented by its state: the nation-state. The nation chooses; the nation acts; the nation suffers tragic losses, achieves glorious victories, and marches toward a splendid future.
The nation is personified and thought of as a protective and semi-divine creature who, while lovingly concerned (we are solemnly assured) with the individual’s welfare, demands that that welfare be subordinated, no questions asked, to its own. Think “Uncle Sam.” Think the various “Motherlands.”
If we must have nations, let us at least have each nation leave its citizens free to engage in peaceful commerce with whomever these individuals choose and on whatever terms they wish and can, on their own, arrange. Trouble is, the very existence of nations creates a false perception that commerce with foreigners differs from commerce with fellow citizens. And thus nationalism fuels suspicion of commerce with foreigners – a suspicion that, unfortunately, usually is as strong as it is stupid.