From the literary heritage of St. John of Kronstadt for this edition, words dedicated to sobriety, or guarding the heart, have been selected and systematized. This spiritual work allowed Fr. John's ability to maintain a prayerful attitude in the bustle of the world elevated him to the heights of holiness. Father John explains the role of the heart in spiritual life, teaches us to understand its language and distinguish good from evil with the heart. Advice about. John are important for the modern Christian, who, amid many worries and troubles, wants to keep his heart pure for God.