This is another ballad with the moving bass line.  The idea is probably borrowed from "To His Coy Mistress", by the lyric poet Andrew Marvell.  When it was finished, I thought "this is mighty short", but the other side of my mind said "no, you've said all there is to say, so just quit."  Maybe there's a lesson there: "when you've said enough, don't garbage it up with more!  Just put your pencil down!"