The foundation of the library dates back to the 5th century as an emanation of the Scriptorium of the Schola majoris Ecclesiae, that is, the book workshop where books on parchment were drafted and composed by the Canons of the Cathedral Chapter, subsequently necessary for the education of future priests. One of these priests, Ursicino, who had the minor order of Reader, after finishing transcribing the Vita Sancti Martini, a work by Sulpicius Severus, and the Life of the Theban hermit Saint Paul, composed by Saint Jerome, at the conclusion of the so-called Ursicino codex declares to have completed his work on August 1, 517. This is an important document as it presents, already in the early years of the 6th century, a well-organized hierarchical structure within the Scriptorium. However, the presence of even older codices, such as Augustine's De Civitate Dei and Gaius' Institutiones (the only one in the world), trace the foundation of the library to at least the previous century.