I'm guessing this message (click) from Stewie above is the best answer to Sandy's question. Jimmie Driftwood, the songwriter himself, says, "Let each individual interpret it for himself." But look at Stewie's post for Driftwood's interpretation.

Here are some recordings of the song:

• Jimmie Driftwood
• Peter, Paul & Mary
• Odetta
• Robert Earl Keen, Jr.
• Chris Thile & the Live from Here Cast