St. John of the Cross became a monk at the age of 21, taking on the habit of the Carmelite friars at Medina. St. John of the Cross was known for his devotion to suffering and self-humiliation to glorify God. He slept in a small, dark cell with a hollow board for his bed, similar to that of a grave or a casket. He wore a hair shirt that pricked his body until he bled. His fasts and mortification were regarded as incredible, even for his time. By all of these means, he studied how to die to the world in order to live for Christ.

St. John of the Cross had two maxims. His first was that, to attain perfection, a person studied Jesus Christ and desired to imitate him. St. John’s second maxim was to mortify the senses in all things, denying himself whatever did not seem to contribute to the glory of God. When Teresa of Avila heard about John, she set about reforming the Carmelite order. Soon after she founded her first monastery for men, John of the Cross responded to her call and entered the new rule on Advent Sunday, 1568. This was the beginning of the Barefooted Carmelite Friars. John, in reflecting on the cross, experienced internal and external trials, yet he was persistent in holding fast to his devotional rules.

In his austerity, John was considered a rebel and a threat to the church. He was imprisoned as an apostate, yet he did not yield to despair. It was Teresa of Avila who eventually secured his release from prison. His major contribution to devotional literature is The Dark Night of the Soul.