Books are heavy. This simple fact is well known to anyone who has had to move the contents of a bookcase, but weight is only the most obvious of their disadvantages. Books take up space that is at a premium in small houses, and they require constant maintenance to preserve them from time, rot, damp, dust, heat, cold and predators of every sort. They are often badly produced, expensive, awkward to handle, ugly, prone to collapse and full of mistakes. They also have a mysterious life of their own, breeding and travelling at will. However often you winnow your shelves, they fill up again before you know it, in my case in double rows. While valued volumes disappear, the unwanted multiply, seemingly of their own volition. You end up with three copies of The Bible in Spain but not one of The Bible of Amiens.

Books are, in short, a bloody nuisance. So why on earth would anyone want to collect them? And why do some people pursue them obsessively – an obsession that is all the stranger because many of the keenest collectors know everything about the provenance of their books, look at them,