As a young man, Cassian and his friend Germanus visited the hermits living in the Egyptian desert. After many adventures, he finally ended up in southern France, where he wrote a book called The Institutes, which gives practical directions for organizing a monastery, and The Conferences, which records the spiritual wisdom of the desert fathers he had visited as a youth. Good, practical spiritual wisdom, very down to earth and insightful.
Augustine drifted away from the faith, but after his conversion, and ordination as a bishop in North Africa, he wrote the Confessions to confess not only his sinfulness, but, more importantly, his gratitude for the grace of God in his life.
This is his set of guidelines for the life of monks. It is based on previous writings, and upon his own reflections upon life in Christ. Though intended for a limited purpose of guiding a monastery, it is filled with Christian wisdom that applies to us all, especially concerning life in any Christian community, and the proper balance in the Christian life.
Some English writer wrote this marvellous account of the simple prayer involved in "a naked intent unto God."
This book is a blunt invitation to conversion, aimed originally at people living in a religious community (and some of its sections reflect that focus), but with lots of hard hitting words for any Christian.
This is not meant to be read form cover to cover. It is the instructions for making a 30 day retreat, but it also can be most helpful to any Christian even when not making a retreat, especially when it comes to rules for discerning God's will.
Using the image of a castle with level upon level of inner rooms from the foul things in the surrounding moat to the light of Christ at the innermost room, Teresa outlines the stages of the Christian life. Other books: he Autobiography, The Way of Perfection. These books were originally intended for contemplative nuns, but their Christian wisdom applies to all.
Also: The Living Flame of Love, and The Dark Night of the Soul. St. John was a great poet, and often his works take the form of commentary upon a poem he wrote. Deep insight into the spiritual life.
Francis was a great bishop and spiritual director. His letters of advice to a laywoman at the royal court were gathered and modified to create The Introduction. The first part is influenced by the Spiritual Exercises, and then the rest of the book provides practical guidance in the battle against sin, and in the life of virtue. The style and the imagery may at first appear dated (this is less so if you get a good modern translation), but it is a treasure of spiritual wisdom, and one intended not just for monks and nuns but for lay people.
Simple notes of a lay brother who was constantly aware of God's presence, especially in the midst of his daily tasks.
A classic, with excellent practical advice about dealing with temptation and sin, and growing in virtue.
Notes from this French Jesuit's talks to sisters develop the theme of total abandonment to God's will, day by day. An aspect of his teaching is the concept of the sacrament of the present moment: being conscious of God's presence not in past or future, but in the present moment, where we abandon our lives to his will.
An anthology of the writings of many early spiritual writers, especially of the eastern church, first put together on Mount Athos in the eighteenth century, and now largely translated into English. Good reflections especially upon the Jesus Prayer.
A wonderful introduction to prayer by a Russian Orthodox Archbishop.