St. John of the Cross (San Juan de la Cruz) was a Carmelite monk. He was a friend of St. Teresa of Avila, although they seldom met face to face; and like her, he was dedicated to bringing back the more rigorous old Carmelite rule for those who wished to follow it. His difficulties were even greater than hers, however, as at one point he was actually captured and imprisoned by some of his Carmelite brothers who didn’t like his ideas.
Also like her, he was a mystic and writer. His poems are classics of Spanish literature.