This eBook has been formatted to the highest digital standards and adjusted for readability on all devices. The Interior Castle, or The Mansions, was written by St. Teresa of Ávila, the Spanish Discalced Carmelite nun and famed mystic, in 1577 as a guide for spiritual development through service and prayer. Inspired by her vision of the soul as a diamond in the shape of a castle containing seven mansions, she interpreted life as the journey of faith through seven stages, ending with union with God.