Why is it so gut-wrenching?

The game mentioned.
I still have it.
I was just listening to a piece on the radio about a show that is being put together to commemorate 9/11 in the US. Listeners have been asked to select a piece of music they feel works best for such memories. By far and away the most popular choice is Samuel Barber's Adagio for Strings.

I agree absolutely, but can anyone explain why this piece is so visceral? How do a few notes, strung together in a particular way, manage to cut through the emotions so surgically? I know music always influences the emotions - there are plenty of songs that bring a smile to the face, for example. But Adagio for Strings (and for me, even more so Barber's vocal adaptation, the Agnus Dei) is unequalled in its ability to manipulate.

A long time ago (in a galaxy far, far away) one of the things I used to do to bring in the pennies was review computer games. It was as the backing track to the opening sequence of a game that I first came across this piece (back then it wasn't played on the radio anywhere near so often). The backstory of the game involved the evacuation of a planet, and as the screen showed the ship departing from a dying world, the backing track of Barber's Agnus Dei worked magnificently.

I don't know if anyone has researched it, but I'd be fascinated to know why this particular piece is so powerful.

So go on. Have a wallow: