St. Teresa of Ávila (1515-1582) was a revered Spanish mystic, theologian, and Carmelite nun. Together with St. John of the Cross, she advocated for reform in the Carmelite order, which led to the establishment of the Discalced (“barefoot”) Carmelites in 1593. She is one of the foremost proponents of mental prayer (the Catholic practice of loving God through meditation and contemplation—a silent dialogue with God). According to St. Teresa, mental prayer (“Devotion of Heart”) is the first of four stages in the ascent of the soul. It is followed by Devotion of Peace (the surrender of personal will), Devotion of Union (absorption in God), and Devotion of Ecstasy (what yogis call samadhi). Her writings are considered to be an important part of Spanish Renaissance literature as well as Christian mysticism. In her most renowned work, The Interior Castle, she wrote, “It is foolish to think that we will enter heaven without entering into ourselves.”