In 1836, Christian August Brandis published excerpts from an anonymous commentary on Porphyry’s Isagoge, the introductory text in the Byzantine logical curriculum. Because much of the material in the commentary draws from the Late Antique commentators known as David and Elias, the work of the anonymous Byzantine has languished in relative obscurity ever since. This chapter offers a new edition of the prolegomena of the commentary and shows their importance not only for logic in Byzantium but also for the study of the rhetorical curriculum and the Corpus Hermogenianum itself. Brandis chose not to publish several passages from the prolegomena, indicating these omissions only by an ellipsis. A study of the manuscripts has shown that those elided passages in fact offer an extensive discussion of the rhetorical curriculum and of the role that Porphyry’s Isagoge should play in teaching rhetoric. The Commentator emphasizes in particular how the lessons learned in the Isagoge should be considered prerequisites for the rhetorical curriculum, consisting of the Corpus of Hermogenes, beginning with the Progymnasmata of Aphthonius. These anonymous prolegomena, especially in their unpublished sections, thus offer an important witness to how logic was taught in conjunction with the Corpus of Hermogenes in the Byzantine classroom.