St. John of the Cross was a Spanish mystic and poet born in 1542. He is best known for his writings on the spiritual journey and the concept of union with God. As a member of the Carmelite order, he worked to reform the community, emphasizing a life of prayer and contemplation. He is celebrated for his profound poetry and spiritual treatises, including "The Dark Night of the Soul." St. John of the Cross was canonized in 1726 and declared a Doctor of the Church in 1926, recognizing his significant contributions to Christian mysticism and spirituality.