The philosophy taught at the University of Salamanca in the 1560s held that the mind starts out blank and learns nothing except through the senses. John of the Cross studied there from 1564, and he never gave that teaching up. In The Ascent of Mount Carmel he repeats it in a picture: the soul in the body is like a prisoner in a dark cell who knows only what he sees through its windows. If the soul refuses what the senses bring, it is left in darkness. From this John drew the conclusion that runs through all his prose. God is not among the things that come in through the windows, so a person who wants God must close them on purpose and go forward in the dark.
Union with God, he held, cannot be reached through anything the mind can picture, remember or grasp, because nothing created is like God. The soul must therefore be emptied — first of its cravings for things, then of its reliance on its own understanding, memory and will. These three he hands over to faith, hope and love. Visions and revelations go too: he tells his readers to refuse them even when they may come from God. This emptying is what he calls the night. The dryness it brings to prayer is a sign that the soul is on the road, and no cause for alarm. On a sketch of a mountain he drew for the nuns he directed, the straight path up the middle is marked nada, nothing.
He came to the friars from poverty. Born Juan de Yepes, he lost his father, Gonzalo, in 1545, when he was about three; Gonzalo's wealthier relatives had disowned him when he married Catalina Álvarez, and he worked as a weaver beside her. The family settled at Medina del Campo, where the boy worked in a hospital and studied with the Jesuits. He joined the Carmelites in 1563, and by the time he was ordained a priest in 1567 he planned to leave them for the Carthusians, an order of hermits who live in silence. That year, at Medina, Teresa of Ávila told him about her reform of the Carmelites and persuaded him to join it instead. On 28 November 1568 he helped open its first house for friars at Duruelo, and took the name John of the Cross.
The reform cost him his freedom. On the night of 2 December 1577 Carmelites opposed to it seized him in Ávila, where he was confessor to the nuns of the convent of the Incarnation, and locked him in their priory at Toledo. For the better part of a year he was held in a cell about three metres by two and flogged before the community. There he composed poems in his head. He escaped on 15 August 1578.
The poems sit uneasily beside the doctrine. The man who told his readers to let go of every image wrote love poems full of them: a woman slipping out of a sleeping house at night, a bride asking the woods where her lover has gone, a flame that wounds. His four major treatises are commentaries on his own verse, in plain prose divided into books, chapters and numbered sections. In the prologue to the Canticle he leaves each reader free to take from the stanzas what their own spirit allows.
In June 1591 a chapter of the order in Madrid stripped him of his offices. He had opposed Nicolás Doria, who then governed the Discalced Carmelites, the branch of Teresa's reform, on two questions: the expulsion of Jerónimo Gracián, Teresa's close collaborator, and whether to give up the direction of the nuns. He was sent to the remote friary of La Peñuela and died at Úbeda on 14 December 1591, aged forty-nine, having published nothing.
The first edition of The Ascent of Mount Carmel, The Dark Night of the Soul and The Living Flame of Love appeared at Alcalá in 1618, with passages softened by its editor, the Carmelite Diego de Jesús. Within five years Seville's Inquisition was finding it in the houses of suspected alumbrados, spiritual circles accused of claiming direct inspiration from God; after the Augustinian theologian Basilio Ponce de León answered the charges in 1623, the Inquisition's council in Madrid let the case drop. A Spiritual Canticle of the Soul and the Bridegroom Christ came out in French at Paris in 1622 and in Spanish at Brussels in 1627. His shorter pieces — precautions, letters, maxims and poems — went into the second volume of the English Complete Works that his Victorian translator David Lewis published in 1864.
He was canonised in 1726 and declared a Doctor of the Church in 1926. T. S. Eliot set a sentence from the Ascent at the head of Sweeney Agonistes. Edith Stein, the philosopher and Carmelite nun, was writing The Science of the Cross, a study of him for the fourth centenary of his birth, when the Gestapo took her from her convent in August 1942. In 1948 Karol Wojtyła, later Pope John Paul II, defended a doctoral thesis in Rome on the doctrine of faith in John of the Cross.