[4] Faithful to the admonitions of his pious mother, three of whose letters to him are mentioned in his Vita, Desiderius led at court the serious holy life of a monk, and administered his office with great fidelity.
He was a zealous promoter of monastic life and founded a monastery in the vicinity of Cahors, the church of which was dedicated to St. Amantius; later on the convent was called after its founder St Géry (i.e. Dierius, from Desiderius).
The finished style of his building was notable, not of vernacular materials of wood, wattle and thatch, but in the manner of the ancients out of squared and hewn stones, not indeed in our Gallican fashion, but just as a whole circuit of ancient walls is wont to be built; thus from the foundations to the topmost pinnacle he completed the work with squared stones' (quoted in Greenhalgh) He also built an aqueduct to serve Cahors, and rebuilt the walls and towers (castella) that protected the city, as well as the Castrum Mercurio in Cahors itself.
A Vita of Desiderius has been composed around the late 8th century by an anonymous author, possibly a monk from Saint-Géry near Cahors, written on the basis of older documents.
[7] Anthyme Saint-Paul, in his Histoire monumentale de la France, nominated Didier as "le dernier des Romains" ("the last of the Romans") because of his building activities as bishop.
Didier's lifelong correspondence with other aristocrats that he befriended in his youth also represents the very end of ancient epistolography dating back to the Hellenistic period.
His small literary circle clearly attempted to preserve Roman heritage and traditions going back to Vergil and Homer, and the ability to speak the language of the past was valued.