This online rhetoric, provided by Dr. Gideon Burton of Brigham Young University, is a guide to the terms of classical and renaissance rhetoric. This site is intended to help beginners, as well as experts, make sense of rhetoric, both on the small scale (definitions and examples of specific terms) and on the large scale (the purposes of rhetoric, the patterns into which it has fallen historically as it has been taught and practiced for 2000+ years).
This article appears in the Holt Elements of Literature Sixth Course: Essentials of British and World Literature text alongside Beowulf and an excerpt from John Gardner's Grendel. It is a good companion piece for Beowulf.