The word 'hypochondria' has travelled from meaning physical ailments in a particular region of your body, to ones that are only in your mind. It has been in fashion, and thoroughly out; it has been subject to a range of treatments; it has been lucrative for quacks; and it's a very understandable form of anxiety - which I have, and so does Caroline Crampton, author of the new book A Body Made of Glass: A History of Hypochondria.