What is the author's style in Dark Night of the Soul by St. John of the Cross?

St. John of the Cross wrote the Dark Night of the Soul as an instructional book, which is used by the Catholic Church to teach others about this crisis of the soul. St. John's intent was to share the occurrences of the dark night and bring comfort to others by teaching that these painful times are sent by God and intended to make the spirit stronger and closer to God.