his essay on "Clio, a Muse" that "history is not merely the accumulation and interpretation of facts -- hard enough, that, in itself -- but involves besides the whole art of book composition and prose style." 6 Such a double task has been a goal for me, and I hope I have not failed too badly on either score. There is another admonition that I have kept in mind and that I also want to quote. It comes from Ronald Knox, an author of considerable brilliance and versatility whom I have long admired. It is simply the obvious truth that "books are meant to be read, and the first quality of a book is that people shall read it and want to go on reading it." 7 That may be too ambitious a hope for essays such as these, but in writing them I have tried to some extent to reflect this awareness.