Francisco de Zurbarán: John of the Cross. A conflict within the Carmelite religious order – he and his friend St. Teresa of Avila favored a stricter observance than the General Chapter was willing to grant – led to his being seized and being imprisoned in Toledo, where he spent his time writing luminous poetry such as The Spiritual Canticle. He wrote also about the “dark night of the soul,” in which even the most faithful seeker of God can experience alienation, doubt and temptation. It must be faced and endured, he said, as the final assault of the enemy.