The Interior Castle is the mysterious masterpiece of Teresa de Jesús-also known to the world as St. Teresa of Ávila-a 16th-century mystic whose profound personal experiences continue to guide seekers of every generation. Teresa addresses her fellow Sisters in her writing, leading them on an extraordinary journey through the "mansions" of the soul, culminating in union with God. Centuries later, we continue to learn from her mystical experiences-described with humility and often in the third person-gaining an intimate glimpse into the heights of divine love and the depths of human longing. Renowned for her visionary ecstasies and frequent bouts of levitation during an age when the West began to secularize, St. Teresa nonetheless endured great physical and spiritual pains, embracing them as gifts from God. Accepting these trials with unwavering faith, she famously prayed, "Lord, either let me suffer or let me die," revealing a soul fully surrendered to divine will. This new translation of The Interior Castle, taken from the original 16th-century Spanish, brings St. Teresa's timeless reflections into our modern era. It preserves the elegance and authenticity of her voice while offering readers an accessible entry into one of the greatest treasures of Christian spirituality.