From its inception, Christianity has been known as the religion of the cross. Among Christians, the cross is a symbol of Christ's passion and its part in the economy of salvation. To non-Christians, it is what St. Paul termed it: a scandal and a folly. How did a token of degradation inflicted largely on slaves, violent criminals, and insurgents evolve into the purest symbol of Christian faith? What transformed an emblem of vile death and suffering into an exalted object and a prompt to great monuments of Western art? That metamorphosis, enacted in theology and the arts, is interwoven with the history of Western civilization. Accordingly, the saga of this symbol, of its uses and reactions to it, from patristic times to the present, is essential. The telling of it requires rigor and breadth. A theologically complex subject with wide historical reach does not reduce easily to a pocket reference.