I've been learning about Bach recently and watched this movie on youtube about his life (recommended!).
Now I'm totally hooked on the little intro tune. Does anybody know what it is?

Someone in the youtube comments said it's a variation of "Bist du bei mir" but I can't find it anywhere and it doesn't really sound like that.

https://www.youtube.com/watch?v=Gism1T5Rvuc

Cheers!