o donnell: some of the world s finest classical music might have been lost forever, were it not for a woman who has spent nearly two decades restoring it to prominence. adriana diaz on the quest to pi by some or black rea reporter: at brooklyn s ryder elementary school, students in the harmony program got a front- row seat to world-class violinist rachel barton pine. she played music by composers like ignatius sancho, a self- taught british slave. and chevalier de saint-georges, who was once the envy of mozart. this music, a lot of it hasn t been established.