I first heard the traditional melody on which the first and last movements are based on an album by the progressive rock band Gryphon, who title it "The Unquiet Grave". It is thought to date from the fifteenth century, and deals with a young man's grief over the death of his lover, and a "year and a day" spent mourning at her grave until she tells him to leave her in peace and enjoy life while he has it.

The melody has been used by many composers and artists. It is clearly a haunting refrain,...