The thornbush is the old obstacle in the road. It must catch fire if you want to go further.
I haven't read the 'Twilight' books. But it's everywhere so I feel like I know it. Edward, Bella, Jacob, etc. but... I haven't read them.
With the piano I'm completely in control of the gestural situation-not that I'm going to play the piece myself, but I know what's difficult, what's impossible.