A Book Dragon — Donn Kushner

Nonesuch, the last in a line of dragons, uses his unique ability to change in size to survive for six centuries, during which time he observes such different humans as a medieval monk, an eighteenth-century London chemist, and a modern American bookseller.Nonesuch, the last of a family of dragons, survives six centuries, including visits to plague-stricken London and a modern bookstore, without being discovered