Favorite Piece?

Watching a clip about the piece that stops various classical music lovers in their tracks, on hearing it.  Each one had a different one, and I got to thinking: how would I answer that question?  I'm likely to change my mind, depending on what I had been doing ...

But here's one favorite: the last chorus of the St. Matthew Passion by Bach— Wir setzen uns, mit Tränen nieder ... I have to check that title; I've forgotten it.  The disciples, and the two choirs (that work requires two choirs, and two orchestras and two organs), are seated symbolically at Jesus's grave, and are weeping. 

There is a powerful tune that keeps returning (these sorts of tunes are called a ritornello.)  It's in two parts.  One part starts in the major key, and ends in the minor.  The other one is almost a twin of the first, except that it starts in the minor, and finishes in the major. 

It's sad, but I love it!  I ought to give you a link to a recording, and maybe I will, later. 

Archie