Before 1648 (the Peace of Westphalia), there weren’t exactly “countries” in the way we think of them today. But there were still kingdoms, empires, etc… There was still such a thing as “immigration,” even though it was a bit different from today.

What does the Angelic Doctor have to say about immigration? Something, it turns out. St. Thomas addresses the question in the context of a discussion on the judicial precepts of the Jews (viz., the “civil law” of Israel as given by Moses). The question he is responding to is, “Whether the judicial precepts regarding foreigners were framed in a suitable manner?” Of course, he says they are, because God gave them through Moses. Hello. So that’s the sed contra, the argument from authority.

Here is the Answer:

“I answer that, Man’s relations with foreigners are twofold: peaceful, and hostile: and in directing both kinds of relation the Law contained suitable precepts. For the Jews were offered three opportunities of peaceful relations with foreigners. First, when foreigners passed through their land as travelers. Secondly, when they came to dwell in their land as newcomers. And in both these respects the Law made kind provision in its precepts: for it is written (Exodus 22:21): ‘Thou shalt not molest a stranger [advenam]’; and again (Exodus 22:9): ‘Thou shalt not molest a stranger [peregrino].’ Thirdly, when any foreigners wished to be admitted entirely to their fellowship and mode of worship. With regard to these a certain order was observed. For they were not at once admitted to citizenship: just as it was law with some nations that no one was deemed a citizen except after two or three generations, as the Philosopher says (Polit. iii, 1). The reason for this was that if foreigners were allowed to meddle with the affairs of a nation as soon as they settled down in its midst, many dangers might occur, since the foreigners not yet having the common good firmly at heart might attempt something hurtful to the people. Hence it was that the Law prescribed in respect of certain nations that had close relations with the Jews (viz., the Egyptians among whom they were born and educated, and the Idumeans, the children of Esau, Jacob’s brother), that they should be admitted to the fellowship of the people after the third generation; whereas others (with whom their relations had been hostile, such as the Ammonites and Moabites) were never to be admitted to citizenship; while the Amalekites, who were yet more hostile to them, and had no fellowship of kindred with them, were to be held as foes in perpetuity: for it is written (Exodus 17:16): ‘The war of the Lord shall be against Amalec from generation to generation.’

In like manner with regard to hostile relations with foreigners, the Law contained suitable precepts. For, in the first place, it commanded that war should be declared for a just cause: thus it is commanded (Deuteronomy 20:10) that when they advanced to besiege a city, they should at first make an offer of peace. Secondly, it enjoined that when once they had entered on a war they should undauntedly persevere in it, putting their trust in God. And in order that they might be the more heedful of this command, it ordered that on the approach of battle the priest should hearten them by promising them God’s aid. Thirdly, it prescribed the removal of whatever might prove an obstacle to the fight, and that certain men, who might be in the way, should be sent home. Fourthly, it enjoined that they should use moderation in pursuing the advantage of victory, by sparing women and children, and by not cutting down fruit-trees of that country.”

Read the rest of the Article here. The Objections and Replies are interesting as well… though you might gasp at one or two!