Who is St. John of the Cross from Dark Night of the Soul and what is their importance?

St. John is the author of Dark Night of the Soul. He was a Spanish priest and friar of the Carmelite order of the Catholic Church. He is considered to be one of the co-founders of the Discalced Carmelites, a sect of the Catholic Church. In 1675, eighty-three years after his death, St. John was beatified, which means the Catholic Church acknowledged he went to heaven when he died. It also indicates St. John has to power to intercede with God on the behalf of believers on earth. St. John is also named among the twenty-three doctors of the Catholic Church.