Around 420, at the request of Bishop Castor of Apt in Gallia Narbonensis, Cassian wrote two major spiritual works, the "De institutis coenobiorum" ("Institutes of the Coenobia") and the "Conlationes" or "Collationes patrum in scetica eremo" ("Conferences of the Desert Fathers"). In these, he codified and transmitted the wisdom of the Desert Fathers of Egypt. The "Institutes" deal with the external organization of monastic communities, while the "Conferences" deal with "the training of the inner man and the perfection of the heart".