Few works have shaped a national literature as thoroughly as the Poem of the Cid has shaped the Spanish literary tradition. Tracing the life of the eleventh-century military commander Rodrigo Diaz de Vivar, called El Cid (from the Arabic Sayyidi, "My Lord"), this medieval epic describes a series of events surrounding his exile. The text of the poem survives in only one early-thirteenth-century manuscript copied by a single scribe, yet centuries later the figure of the Cid still was celebrated in the Spanish popular ballad tradition. Today almost every theme that characterizes Spanish...