In today’s catechesis, we discuss the sixteenth-century Spanish Carmelite mystic, Saint John of the Cross. John was born into a poor family. As a young man he entered the Carmelites and was ordained priest. Soon afterwards, he met Teresa of Avila in what was a decisive encounter for them both, as they discerned plans for reforming the Carmelite Order. He became confessor at Teresa’s monastery, and together they developed a rich articulation of the workings of the Lord upon the soul in the spiritual life. Despite persecution and misunderstanding from within his own Order, John produced some of the most illuminating and insightful treatises in all of Western spirituality. His four major writings are The Ascent of Mount Carmel, The Dark Night of the Soul, The Spiritual Canticle, and The Living Flame of Love. One of the themes much developed by John was that of the purification of the soul: by means of created things, we can discover traces of the living God in this world. Faith, however, is the unique means by which we can come to know God as he is in himself. The demanding process of purification, at times active and at others passive, requires our determined effort, but it is God who is the real centre; all man can do is dispose himself and humble himself before the loving work of God in the soul. In this sense, John is for us a model of humble dedication and of faithful perseverance on the road to spiritual maturity.