"So softly dark and darkly pure.
Which follows the decline of day,
As twilight melts beneath the moon away."
It's that time of day which is the inspiration for this episode of What's in a Song, our occasional NPR series about one song and its story. Mary Chapin Carpenter's new song is "Twilight," about her sense of home and taking walks at the magical time of day when the darkness of night is coming on.