Last night I hosted a talk by Sean Gabb, and ripped off a report of it for Samizdata. I fear I exaggerated the speed and extent of the collapse of the Eastern Roman Empire, following the plagues of the mid sixth century. But the impact of plague on events was most interesting.

Basically, when a political system is presided over by a tiny elite of literate conquerors who speak one language, but who rule people who speak other languages, plague spells deep trouble for that elite.

This elite doesn't perpetuate itself biologically. It perpetuates itself by teaching its alien language to a regular few of the upwardly mobile locals. So teachers are a key part of this process.

When plague strikes, half the elite die, including half the teachers. But the other half of the teachers then have to turn their hands to more important matters, filling in for their former dead superiors. Thus, the process of replenishment and perpetuation ceases. In large parts of the old Eastern Roman Empire, ruled by a Greek speaking elite, this elite melted away, throughout what we now call the Middle East.

And to me, even more of a revelation, the Black Death (mid fourteenth century) killed off French as the governing language of England. I never knew this.