Hi, Lassie, this song came out on the 1967 PP&M album, Album 1700. I believe this was the first album PP&M recorded with songs that were primarily from modern songwriters. Noel Paul Stookey usually writes songs from his own imagination, not based on other songs or pieces of literature. The meanings of his songs are usually quite cryptic. I don't know if you'll find an explanation of the song - it's not explained in the album notes.
-Joe-