St. John of the Cross was the great ally of St. Teresa, whose feast is on October 15, in the reform of the Carmelites; he introduced the primitive observance among the friars as she did among the nuns. For this reason he was subject to great persecution. He was a man of complete self-renunciation, great love of the Cross and profound spirit of prayer; his mystical writings have made him the Doctor of the contemplative life. He died in 1591. Pius XI proclaimed him a Doctor of the Church in 1926.