I think it is Edgar Allan Poe who says that while a plain thing may on occasion be told with a certain amount of elaboration of style, one that is unusual in its very nature is best related in the simplest terms possible. I shall adopt the second of these methods in telling this story of my friend, Derwent Rose. And I will begin straight away with that afternoon of the spring of last year when, with my own eyes, I first saw, or fancied I saw, the beginning of the change in him.