The “Diary” is one of the gems of mystical literature. Saint Faustina Kowalska wrote it in Vilnius and Cracow in 1934 – 1938 as Jesus had commanded her to do so directly.
In the “Diary” Sister Faustina described her spiritual life, which was especially deep, reaching the summit of union with God in the mystical betrothal. She depicted how deeply she came to know the mystery of the Divine Mercy and how she contemplated it in her daily life. She also wrote about the struggle against the weaknesses of human nature and difficulties pertaining to the prophetic mission. Above all, the “Diary” contains the message of God’s merciful love for man, which Sister Faustina was to pass on to the Church and the world. Therefore, this is a special work, as Holy Father John Paul II said, “the gospel of mercy written from the perspective of the 20th century”.