One day you are on top of the world. You are young, you are strong, you are beautiful. But then, slowly and almost imperceptively, your youth fades, your strength slackens and the person you see in the mirror no longer glows the way it once did. "Where did your long hair go / Where is the girl I used to know," Brian Wilson sang, mournfully. Eventually, life plays a cruel trick on us: just when we think we've got the world by the tail, it all gets taken away. No one is exempted, no one is immune.