Teresa of Avila wrote several books during her life that have become spiritual classics. Interior Castle (1577) unveils a profound spiritual vision in which Teresa saw the soul as ""a castle made of a single diamond . . . surrounded by six mansions the soul must traverse on its journey to the center of the castle and union with God."" One approached the seventh mansion in the center, where the King of Glory dwells, by going through the other mansions of Humility, Practice of Prayer, Meditation, Quiet, Illumination, and Dark Night. In each of the seven mansions readers will experience a deepening desire to know God more intimately by conforming their wills to His will.