Letter 28
To my dear friend in the faith,
Your request for recommendations on theological reading for a priest who wants to deepen his formation is one I am glad to respond to.
For the understanding of scripture: begin with the commentaries of Gregory the Great, whose Moralia in Job and Pastoral Rule are the most practically useful theological texts written in the past hundred years. Gregory writes for the man who is actually doing the work of Christian ministry, not for the academic theologian, and his clarity and depth together are remarkable. After Gregory, Augustine's commentaries on the Psalms and on the Gospel of John, and Jerome's commentaries on the prophets.
For the understanding of the Christian life: Cassian's Conferences and Institutes, which are the best existing guide to the inner life of prayer and virtue. Benedict's Rule, which is the best existing guide to the outer structure of Christian community.
For the understanding of theology proper: Augustine's On the Trinity is the necessary work, but it is demanding. Approach it with patience and a good commentary.
The works of Isidore of Seville — particularly the Etymologiae and the Sentences — are invaluable as reference works and as orientation in the whole tradition. No priest should be without them.
Your brother,
Desiderius
Modern English rendering for readability. See the 19th-century translation or original Latin/Greek for scholarly use.