On Oct. 15, Roman Catholics celebrate the Spanish Carmelite reformer and mystic St. Teresa of Avila, whose life of prayer enriched the Church during the 16th century counter-reformation. Teresa Sanchez Cepeda Davila y Ahumada was born in the Castilian city of Avila during the year 1515,  the third child in a family descended from Jewish merchants who had converted to Christianity during the reign of King Ferdinand and Queen Isabella. Her father Alphonsus had become an ardent Catholic, with a collection of spiritual books of the type his daughter would later compose herself.As a child, Teresa felt captivated by the thought of eternity and the vision of God granted to the saints in heaven. She and her younger brother Rodrigo once attempted to run away from home for the sake of dying as martyrs in a Muslim country, though they soon ran into a relative who sent them back to their mother Beatrice. When Teresa was 14, her mother died, causing the girl a profound grief that prompted her to embrace a deeper devotion to the Virgin Mary as her spiritual mother. Along with this good resolution, however, she also developed immoderate interests in reading popular fiction (consisting, at that time, mostly of medieval tales of knighthood) and caring for her own appearance. Though Teresa's spiritual directors in later life would judge these faults to be relatively minor, they still represented a noticeable loss of her childhood zeal for God. Alphonsus decided his teenage daughter needed a change of environment, and sent her to be educated in a convent of Augustinian nuns. Teresa found their life dull at first, but soon came to some understanding of its spiritual advantages. Illness forced her to leave the convent during her second year. But the influence of her devout uncle Peter, along with her reading of the letters of the monk and Church Father St. Jerome, convinced Teresa that the surest road to salvation lay in forsaking marriage, property, and worldly pleasures completely. Against the will of her father, who wanted her to postpone the decision, she joined the Carmelite Order.Teresa became a professed member of the order at age 20, but soon developed a serious illness that forced her to return home. She experienced severe pain and physical paralysis for two years, and was expected to die when she went into a coma for four days. But she insisted on returning to the Carmelite monastery as soon as she was able, even though she remained in a painful and debilitated state.For the next three years the young nun made remarkable progress in her spiritual life, developing the practice of recalling herself into the presence of God through quiet contemplation. As her health returned, however, Teresa lapsed into a more routine prayer life. While she remained an obedient Carmelite, she would not re-establish this close personal connection to God for almost twenty years. When she was nearly 40, however, Teresa found herself dramatically called back to the practice of contemplative mental prayer. She experienced profound changes within her own soul, and remarkable visions that seemed to come from God. Under the direction of her confessors, Teresa wrote about some of these experiences in an autobiography that she completed in 1565. Teresa had always been accustomed to contemplate Christ's presence within her after receiving him in the sacrament of Holy Communion. Now, however, she understood that the presence she received did not simply fade: God was, in fact, with her always, and had been all along. It was simply a matter of putting herself in his presence, with love and attention – as one could do at any moment. This revolution in her spiritual life enabled Teresa to play a significant role in the renewal of the Church that followed the Council of Trent. She proposed a return of the Carmelites to their original rule of life, a simple and austere form of monasticism – founded on silence and solitude – that had received papal approval in the 12th century and was believed to date back to the Old Testament prophet Elijah. Together with her close collaborator, the priest and writer later canonized as Saint John of the Cross, she founded what is known today as the Order of Discalced Carmelites – “discalced,� meaning barefoot, symbolizing the simplicity to which they chose to return the order after a period of corruption. The reform met with fierce opposition, but resulted in the founding of 30 monasteries during her life.Teresa's health failed her for the last time while she was traveling through Salamanca in 1582. She accepted her dramatic final illness as God's chosen means of calling her into his presence forever. “O my Lord, and my spouse, the desired hour is now come,� she stated. “The hour is at last come, wherein I shall pass out of this exile, and my soul shall enjoy in thy company what it hath so earnestly longed for.� St. Teresa of Avila died on Oct. 15, 1582. She was canonized on March 22, 1622, along with three of her greatest contemporaries: St. Ignatius Loyola, St. Francis Xavier, and St. Philip Neri. In 1970, Pope St. Paul VI proclaimed St. Teresa as one of the first two woman Doctors of the Church, along with 14th century Dominican St. Catherine of Siena.