This is about a woman who has broken her own heart after aborting her baby girl. "I guess I could have carried her but I didn't even try." She needs an angel to do the work of "a mother to love her till the end." The horror comes home after the fact: the never-ending shadows, the no-return Rubicon crossing, the night, the cold, the hopelessness, the realization that her baby girl has never known love. "She'll have to go this one alone / After all that is the only way she's ever known".
And then we get the climax - the Toora Loora duet from seed to rose to cradle to... crow. The irony of two angelic voices offering up all they have for a lullaby. What good is a lullaby without the little one to hear?