From Scrump:

I seem to lack this, and feel that maybe if I had a deadline or something it would force me to work on it.

I think that's what I was trying to get at when I said you had to have something important to say. But maybe what I really meant was you needed to be inspired by something -- and that inspiration needs to be strong enough that it will sustain your interest through the revision process.

But it only has to be inspiring to you. Historians, philosophers and literary critics need not give it so much as a second glance.

And if you're really stuck in the revisions, even so, give yourself permission to put that song away and work on any other ideas that pop into your head. Sometimes, the first idea you get for a song is only the tiny key that unlocks a greater one.