I don't know where that Sun and Moon stuff came from, but as "Three maids a milking would go" the song is on a mid 19th century broadside on the Bodley Ballads website (in Mudcat's Links) [Lucy Broadwood revived? She was good at finding some 'hidden' religious significance in anything that wasn't completely intelligible. I've never put much trust in comments from spinster daughters of ministers since.]