"In a town called Paradise, California ... lived a young man named John Gilbert. I like to think of him as a friend of mine, though we've never met. When he was five years old, John was diagnosed with Duchenne muscular dystrophy. It is a genetic, progressive, and cruel disease. He was told it would eventually destroy every muscle and finally, in a space of ten more years or so, take his life. John passed away a short while ago at the age of twenty-five. Toward the end of his life...he had only enough strength to move a computer mouse with his right hand. But he did that brilliantly. He sent...