Imagine that you are a world-class concert pianist at the peak of your career, someone who has spent years studying and practicing to develop your art. Your fingers respond instantly to your mental commands, flitting along the keyboard with grace and speed. Then one day you feel a stiffness that wasn't there before. You go to a doctor, tests are done, and the diagnosis comes back: Arthritis. Your fingers are destined to become wooden and crippled. From the heights of success and acclaim you will plunge to oblivion.

It h…