I have a theory that pretty much everybody sings the second verse of "Adieu Sweet Lovely Nancy" wrong because the Copper Family wrote it down wrong in their book, and then proceeded to keep singing it wrong because that's what it said in their book, and then everybody else sings it wrong because the Coppers did.

I refer to the second verse, which goes more or less like this, according to pretty much everyone:

And when I'm far upon the sea, you know not where I am,
Kind letters I will write to you from every foreign land.
The secrets of your heart, dear girl, are the best of my good will,
So let your body be where it might, my heart shall be with you still.

What the heck does that even mean? The secrets of her heart are the best of his good will? Huh? How does he KNOW the secrets of her heart, given that we're not talking about letters from her to him? And why are we getting into where her body's going to be? He's the one who's leaving.

My theory is that the verse is really meant to go like this:

And when I'm far upon the sea, you know not where I am,
Kind letters I will write to you from every foreign land.
The secrets of MY heart, dear girl, AND the best of my good will,
So let MY body be where it might, my heart shall be with you still.

That way it makes sense. The secrets of his heart and the best of his good will will be the contents of the letters. She won't know where he is, as he mentioned in the first line, but wherever that is -- let his body be where it might -- his heart will still be with her, because he's sending her all those nice letters.