and kept in the Vatican library. This book, written in capital letters, is one of the earliest surviving manuscripts of any Latin writer. It has the plays in the order An., Eu., Hau., Ph., Hec., Ad. The second group, known as the "Calliopian" (since they seem to have been edited at some time by a certain Calliopus) all date from the 9th century onwards and are written in minuscule letters. This group can be subdivided into three classes. The first class, known as γ (gamma), dates to the 9th, 10th, and 11th centuries and includes manuscripts P (Parisinus), C (Vaticanus), and possibly F (Ambrosianus), and E (Riccardianus) among others. They have the plays in the order An., Eu., Hau., Ad., Hec., Ph.. Manuscript C is the famous Codex Vaticanus Latinus 3868, which has illustrations which seem to be copied from originals dating in style to the mid-third century. Another group, known as δ (delta), has the plays in alphabetical order: An., Ad., Eu., Ph.(=F), Hau., Hec. This consists of 3 or 4 10th-century manuscripts: D (Victorianus), G (Decurtatus), p (Parisinus), and perhaps also L (Lipsiensis). All the remaining manuscripts belong to the "mixed" group and contain readings copied from both γ and δ, and so are of little value in establishing the text. It is thought that the γ group and the δ group go back to two archetypes, both now lost, called Γ (Gamma) and Δ (Delta), and that both of these were copied from a single archetype, also now lost, known as Σ (sigma). According to A. J. Brothers, manuscript A, although it contains some errors, generally has a better text than Σ, which has a number of changes designed perhaps to make Terence easier to read in schools. Both A and the now lost Σ are believed to be derived from an even earlier archetype known as Φ (phi), the date of which is unknown. In addition to these manuscripts there are also certain commentaries, glossaries, and quotations in ancient writers and grammarians which sometimes assist editors in establishing the original reading. The best known of these is the , a commentary by the 4th-century grammarian Aelius Donatus, which is often helpful, although the part dealing with the Heauton Timorumenos is missing. Cultural legacy Due to his clear and entertaining language, Terence's works were heavily used by monasteries and convents during the Middle Ages and the Renaissance.