Sorrow (XS1)

 is Disc 1, Track 11 on the Xenosaga Original Soundtrack and Disc 2, Track 9 on the album. ('Sorrow' is an unofficial translation, as seen in the VGMdb listing of the album.)

It plays in the following cutscenes:
 * Virgil forces the Realians under his control to fight the Gnosis on the Woglinde.
 * Shion argues with KOS-MOS after the latter kills Virgil.
 * Mary and Shelly talk about Jr.'s size after infiltrating the U-TIC Battleship.
 * Shion breaks down after the death of Cherenkov.
 * Shion recognises the top of the Song of Nephilim from her childhood on Miltia.
 * MOMO considers her birth and the machine that made her on Proto Merkabah.