Teresa de Cepeda y Ahumada was born in Avila, Spain, in 1515. At the age of twenty she entered the Carmelite Convent of the Incarnation. While there she battled many serious illnesses, especially between the ages of twenty-eight and thirty. She lived a very devout life at the convent and was known to have occasional supernatural experiences.
In 1555 Teresa experienced what she called a "second conversion," which changed her spiritual life decisively. She began experiencing visions more often, most notably, visions of Christ piercing her heart with a spear. Under the direction of her spiritual counselor, she began working on a project to establish new Carmelite houses that were devoted to the contemplative life. Later John of the Cross worked alongside her in this effort.
Teresa began her writing career with a spiritual autobiography, and it was quickly noticed that she had a gift for writing about the spiritual life in elegant yet simple terms. Her most famous work on prayer is Interior Castle, which she wrote following a vision. In it she describes the soul's journey from the outside of a castle and through many rooms as it strives toward the center room where the soul can unite with God completely. In the spirit of Bunyan's Pilgrim's Progress, Teresa uses allegory to describe the spiritual journey we all face, with its attendant obstacles and joys.