St. Teresa of Jesus, also known as St. Teresa of Avila, is one of the most popular Doctors of the Church. Her teaching on prayer has continued to inspire and guide Christians in their spiritual journeys for over four hundred years.

In The Interior Castle, St. Teresa desribes the road by which she was led, well aware that the others may be led in a different way. In the heavenly Father's house, there are many mansions; not only seven, and many paths lead to them. What gives the work such high value is that it is the result of a most searching inquiry into the various phases whereby a soul is gradually transformed into the likeness of God Himself. Here St. Teresa is at her best. She takes nothing for granted, her own personal experiences are admitted only after having been fully investigated and found to be consistent one with the other, and conformable to the teaching of the Church and the words of Holy Scripture.