The Interior Castle by St Teresa of Avila presents a remarkable description of the entire spiritual life from the first release from mortal sin into Sanctifying Grace through the Mystical Marriage of the soul with Christ as a journey through what she called 'The Interior Castle'.
She sees the soul as a magnificent castle full of spacious and well-lit rooms or mansions each of which leads deeper into the heart of the castle to the seat of the King. However, St. Teresa laments that most people give all their attention to the outer wall of the castle the body ignoring the beauty of the soul within.
St Teresa gives practical advice regarding the early struggles and the temptations to turn back which beset the beginner. She describes each of the seven mansions and urges us forward to love and serve the Divine Majesty, imparting her absolute conviction that progress toward God through prayer is worth vastly more than all the treasures of this earth.
Teresa of Avila
St Teresa of Jesus was born in 1515 in Avila, Spain and entered the Carmelite convent of the Incarnation in 1535, against the wishes of her father. During a serious illness, she practiced mental prayer and started receiving intellectual visions and locutions from Our Lord which continued for the rest of her life. Together with St John of the Cross, she began a reform movement which stressed a return to a traditional rule of poverty and simplicity for Carmelites. St Teresa died on 4 October 1582 in Alba de Torres. She was canonised along with St Ignatius of Loyola, St Francis Xavier, and St Phillip Neri in 1622 by Pope Gregory XV.