Book excerpt: The images devised to accompany medieval commentaries, whether on the Bible or on classical texts, made claims to authority, even inspiration, that at times were even more forceful than those made by the texts themselves. Pictorial prefaces of the twelfth century represent commentaries of their own; they articulate and elaborate complex arguments regarding critical matters of faith. This study examines pictorial programmes in copies of Horace?s poetic works, the Glossa ordinaria, anti-heretical polemics, and Rupert of Deutz?s commentary on the Song of Songs to demonstrate the ways in which they helped to shape understandings of authorship at a critical historical moment.