I ran into an expression "to do back that far" and I couldn't understand the meaning from the context. I tried to find similar ones, but it seems that such expressions are not very common. So, I've found only one example:
"These songs, they're like mystery stories, the kind that Shakespeare saw when he was growing up. I think you could trace what I do back that far. They were on the fringes then, and I think they're on the fringes now. And they sound like they've been on the hard ground."
What does it really mean?
P.S. Another example:
He's absolutely out there, you know, with his theories. Some of them do back far but this deuterium thing that he's nailed at the moment really really does interest me.