Written in 1822 and never completed, Schubert’s “Unfinished” Symphony remains today one of music’s greatest mysteries. Why didn’t Schubert finish it? It wasn’t his premature death at 31 through syphilis; he'd begun the symphony six years before, and just didn’t finish it.

He wrote two movements of what should have been four. The first opens in dark despair, a forlorn oboe looking for comfort amid cloudy black strings. Despite a charming string theme that quickly attempts to divert attention, the music finds no solace — only rumbling storm clouds. There’s even a mood of resignation and sad acceptance to the second movement. And there, halfway through, is the end of the story: the sketches for a third movement are composed of only a few notes.

We’re lucky to have even this. Schubert’s half-symphony was left in a drawer and only found 40 years after his death when his brother sifted through some papers. Various composers have finished the third movement off with what sketches we have and created a fourth in Schubert’s style, but one thing no one will ever know for sure is why he didn’t finish it, since Schubert usually did before starting another one. Perhaps, being the sociable type who could dash off a song on the back of a beermat, he just had too many other friends to see and songs to write for them. Or perhaps he felt that the two movements stand well by themselves — something a lot of people are happy with today.

The piece remains famous today for its despairing opening and the whole “unfinished” business.