Interior Castle is one of the most celebrated books on, mystical theology in existence. It is the most sublime and mature of Teresa of Avila's works and expresses the full flowering of her deep experience in guiding souls toward spiritual perfection. In addition to its profound mystical content, it is also a treasury of unforgettable maxims on such ascetic subjects as self-knowledge, humility, detachment, and suffering. But above all, this account of a soul's progress in virtue and grace is the record of a life-of the interior life of St. Teresa of Avila, whose virile soul, luminous mind, and endearingly human temperament ho]d so deep an attraction for the modern mind.