Born in Avila, Spain, on March 28, 1515, St. Teresa was the daughter of a Toledo merchant and his second wife, who died when Teresa was 15, one of ten children. Shortly after this event, Teresa was entrusted to the care of the Augustinian nuns. After reading the letters of St. Jerome, Teresa resolved to enter a religious life. In 1535, she joined the Carmelite Order. She spent a number of relatively average years in the convent, punctuated by a severe illness that left her legs paralyzed for three years, but then experienced a vision of "the sorely wounded Christ" that changed her life forever.From this point forward, Teresa moved into a period of increasingly ecstatic experiences in which she came to focus more and more sharply on Christ's passion. With these visions as her impetus, she set herself to the reformation of her order, beginning with her attempt to master herself and her adherence to the rule. Gathering a group of supporters, Teresa endeavored to create a more primitive type of Carmelite. From 1560 until her death, Teresa struggled to establish and broaden the movement of Discalced or shoeless Carmelites. During the mid-1560s, she wrote the Way of Perfection and the Meditations on the Canticle. In 1567, she met St. John of the Cross, who she enlisted to extend her reform into the male side of the Carmelite Order. Teresa died in 1582.St. Teresa left to posterity many new convents, which she continued founding up to the year of her death. She also left a significant legacy of writings, which represent important benchmarks in the history of Christian mysticism. These works include the Way of Perfection and the Interior Castle. She also left an autobiography, the Life of Teresa of Avila.

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.