Tie Your Mother Down was built around a riff, which I'd had kicking around for a long time, and I know pretty much where I first played it: it was on top of that volcanic ridge in Tenerife, where I was doing my PhD studies. I had a little acoustic guitar which I'd bought down in Santa Cruz in Tenerife, where we'd lived, and I remember beating out that riff and enjoying it, enjoying the feeling of bending the string as part of the riff. And I sat there watching the sun go down and kind of singing along with it, but I didn't really have a song at that point.