Bud I think it's great that it's been 50 years and we're still talking about it. I'm interested in the fact that duncanwhyte is saying that it was written by a British guy of whom his references was the education at the time and for some of us we have no reference whatsoever to what they are talking about. So this is quite interesting.

The miller is someone who is telling a story and vestal virgins are women of influence back in the day and a Bach influence on the music. Regardless, it became a popular hit in it's day.

So it's something like he met a girl and was kind of messed up, but he knew she wasn't an influential girl and the miller told him more about her which made her turn a whiter shade of pale. He was leaving anyway, so probably was glad he found out the truth.