This work was originally composed by St. Teresa of Avila (1515 - 1582) for her fellow sisters of the Carmelite Order. Although written for nuns it is very much accessible to modern readers. In the work she guides her fellow sisters on the way to union with God through prayer and meditation.

The book offers helpful advise for readers to seek self-perfection. Her words are practical and heartfelt, coming from her personal experience. The book is less formal and gives a more clear form of St. Teresa's theological views than her autobiography or her famous classic, The Interior Castle.