Porphyrio's commentary for school use is the oldest extant commentary on Latin poetry. It forms part of the Graeco-Roman grammatical tradition, and offers a unique insight into 3rd century school and education systems. The investigation gives a detailed account of the educational aims, conditions, contents and methods used and reveals the academic categories on which they were based. The reader thus gains an impression not only of the state of Horace scholarship at the time, but also of the average educational standards of the Roman elites.