This book finds origins of key parts of nearly all the medieval Spanish epics in an ancient myth. The myth of the initiation of the young warrior, shown by Georges Dumezil to be fundamental to the belief systems of widely distributed Indo-European peoples, was variously adapted to shape the action of texts including the Siete Infantes de Lara, the Mocedades de Rodrigo, and the Poema de Mio Cid, in which it accounts for the peculiar behavior of the Infantes de Carrion.

The memory of the same mythic tradition also affords motivation for the central conflict of the Chanson de Roland. In Spain, the earlier epics upheld the values of the heroic age, values necessary for the survival of the warring clan, and were a principal source of the clan members' knowledge of their world and their sense of identity.

The oral presentation of this archetypal lore required a special language capable of re-creating the ritualized behavior of the epic characters and maintaining the ceremonial tone of the performance. The second part of the book studies ways in which the poetic language met that task and evoked a feeling of group unity that absorbed the audience and still works its spell upon today's readers.