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John of the Cross (1542-1591) was a Spanish Carmelite friar and a mystic. He was one of the founders of the Discalced Carmelites, a reformed branch of the Carmelite Order. John is considered one of the most important figures in Christian mysticism. His writings, which include the "Dark Night of the Soul" and "Ascent of Mount Carmel," are widely read and studied by Christians of all denominations.