JUAN DE CASTRO. — Carthusian ascetical writer, born in Toulouse in 1485 into an illustrious family, died at the age of 72 on 6 July 1556. Sent by his father to the University of Paris, he not only earned a doctorate there but also occupied the chair of theology. Among his most assiduous disciples was Ignatius of Loyola, who came to Paris in 1528. The professor formed a close friendship with him, and while instructing the pupil in the principles of sacred science, the pupil—already a master of spirituality—developed the most sublime ascetical theses. Castro resigned his chair, returned to Spain, and on 13 June 1535 entered the novitiate at the Charterhouse of Val di Cristo, where Ignatius later visited him and revealed his plan to found the Society of Jesus. Having made his religious profession on 24 June 1536, he was soon appointed prior of the Charterhouse of Val di Cristo and later prior of that of Porta Coeli.
He wrote the treatise *De innamorabilibus Christi doloribus, quos moriens sponte pro nobis tulit*. His letters were preserved as sacred relics in the Charterhouse of Val di Cristo (*Acta SS. Iulii*, VII, Paris 1868, *Comment. praevius ad acta S. Ignatii*, n. xx).