When you teach a language, you can learn quite a lot about your students without arousing any suspicion.
Because you are supposed to ask questions. Because your students must talk, and you are supposed to help thim.
And you are also supposed to listen.
You mostly listen for mistakes.
But sometimes you also listen for the personality behind the answers to the given questions...

*****
He was my favourite student.
Not the most gifted, not the most diligent one.
But extrememly interesting to listen to.
Every time we had classes, a new path would unfold in front of me, a new path through his personality. Sometimes it led through landscapes I had already visited, sometimes it was a completely new place. And I would sit there and bask in that little secret delight, for I was learning things I was not - strictly speaking - told, I was walking the path I was not supposed to walk.

But then,... which is now,... the classes were over, and we parted. And "here endeth the story" crowns it all.

*****
When you teach a language, you can learn quite a lot.
But perhaps, you shouldn't get too much involved.
Then "here endeth the story" will be just a routine integral part of the process and nothing more.

And nothing more.