Nice article, good research. In medieval Europe there were no passports so people like Copernicus could travel from Warsaw to Padua and back, no problem. One of those liberties restored by the EU. But workers and soldiers were free to go and find employment wherever it was offered. Of course there were other perils and unfairnesses. And then of course in Northern Ireland there was the anxiety abut removing the orbnder, not because it would allow fellow Irishpersons to hang out with each other but because it would undermine the smuggling trade, a rich source of income for folks on the border.