In this searching study, Fr. Murchadh Fr. Ó Madagáin describes the life and thoughts of Fr. Thomas Keating, the Trappist monk who was one of the founders of the centering prayer movement. Centering prayer aims to reclaim the Christian contemplative and mystical traditions after centuries of neglect and to make it available for modern spiritual seekers. Fr. Ó Madagáin traces its roots back to the fourth- and fifth-century Desert Fathers such as Evagrius and John Cassian. He shows how it was used in the medieval classic The Cloud of Unknowing and practiced by saints John of the Cross and Teresa of Avila, then revived by Thomas Merton during the twentieth century. Fr. Ó Madagáin illustrates how, by bringing the insights of contemporary psychology to bear on this ancient method of prayer, Fr. Keating has not only revitalized the contemplative tradition, but also has enabled it to become a powerful tool for people of faith to gain insight into themselves and God, whom Keating calls the “divine healer.” Fr. Ó Madagáin also unpacks the processes at work in centering prayer and clears up some of the common misunderstandings that surround it. Centering Prayer and the Healing of the Unconscious is an essential work for all those interested in the history and practice of centering prayer. In addition to describing the background of this unique and effective practice, Fr. Ó Madagáin offers unique insights into the ideas of one of its leading contemporary teachers and practitioners.