The principles of Spiritual direction laid down in this book are those of St. John of the Cross who exercised his activity as a spiritual director in every walk of life. His instructions concerning the guidance of souls in the way of prayer possess an importance and a capability of arousing general interest.
The principles applied by him in training the spirituality of persons living a secluded life will show themselves equally effective for souls more immersed in the labours of the apostolate. This book emphasises particularly his delicate skill, his scientific solidity and his lofty tone.
Its main theme is the high union of the soul with God, but adds as the only way thereto, our assimilation with and transformation in Christ.