"He himself was not the light." But all of Israel had been waiting for the Light, and of course the Church continues to wait -- joyfully and prayerfully, as tomorrow's Epistle says.
If you're preaching tomorrow, and racing to find a hook, you might consider the American folk blues Midnight Special, about a man in prison watching the train come down the tracks, hoping that it may bring a pardon from the governor, and set him free.
Shine your ever-loving light on me. It's not a bad prayer for Advent.
Like so many folk songs, it has a complicated textual history, and the lyrics are a bit hard to pin down. (Wikipedia background here; lyrics as recorded by the Band and CCR here; Leadbelly version here). And fair warning: Carl Sandburg thought that the song wasn't about waiting for a train to freedom, but about wishing to be hit by the train rather than remain a prisoner. (Still, a chance to talk about the sin of despair).