People often forget how quickly languages change.

Long long ago I worked briefly on an "interactive laser disc" (yes, that long ago) training system that had been commissioned by the State Dept for instruction in Tagalog. They needed a white guy that spoke Tagalog, and I was around. The script had been prepared in the US by a woman who was apparently the senior and most respected teacher of the language in DC. She'd apparently been teaching there for over 20 years.

When we actually looked at the script, it turned out to be virtually unintelligible to anyone who spoke the language in its modern incarnation. Filipinos who read it had vague memories of their grandparents talking like that. For me (having picked up Tagalog on the back streets of Cubao) it was essentially a different language. Any diplomat who actually learned from that script would have been, in effect, learning a dead language.

I wonder if any similar events occur in other languages, particularly those that are spoken over wide areas and with significant local variation, and with languages that are rapidly evolving...