Juan de Yepes was born to a poor weaver's family in Old Castile; his father died when he was a small child, and the family lived in extreme deprivation. He worked as a nurse in a hospital for syphilitics while studying at the Jesuit college of Medina del Campo, and at twenty-one entered the Carmelite Order, taking the name Juan de San Matías.
Drawn to even greater austerity than the Carmelite life offered, he was about to leave for the Carthusians when, in 1567, he met St. Teresa of Ávila. She was twenty-seven years his senior and had just begun her reform of the women's Carmelites. She persuaded him to undertake the same reform for the men. In November 1568, with two companions, he opened the first Discalced Carmelite house for friars at Duruelo, taking the new name Juan de la Cruz.
Persecuted by the unreformed Carmelite establishment, he was kidnapped in 1577 and held in a tiny cell of nine by five feet in a Toledo monastery for nine months. There — by candlelight smuggled in by his jailer — he composed the first thirty-one stanzas of the Spiritual Canticle, some of the greatest religious poetry in the Spanish language. He escaped after nine months of beatings and isolation, and spent the rest of his life writing the commentaries on his own poems that are his theological masterpieces: The Ascent of Mount Carmel, The Dark Night of the Soul, The Spiritual Canticle, The Living Flame of Love. He died at forty-nine of an infected leg.