The charm of this book lies in the fact that it is so obviously the adult sublimation of a boyhood passion for the lands and history of Islam. Mr. Marozzi is now 49, but his prose often has the wonderment of a young man who has devoured a shelf of books and is dying to tell everyone about the things he has read. Like an erudite magpie, he gathers material from every available source—primary texts, both religious and historical, as well as a profusion of secondary ones—and weaves it all together with dexterity.