“Much as the old world believed in pure blood, it had very little of it. Most historic nations conquered prehistoric nations, and though they massacred many, they did not massacre all. They enslaved the subject men, and they married the subject women. No doubt the whole bond of early society was the bond of descent; no doubt it was essential to the notions of a new nation that it should have had common ancestors; the modern idea that vicinity of habitation is the natural cement of civil union would have been repelled as an impiety if it could have been conceived as an idea.”
Walter Bagehot, Physics and Politics (1872).