John of Ruysbroeck was a 14th-century mystic, theologian, and Augustinian canon from the Duchy of Brabant. Born in Ruisbroek, he was ordained a priest in 1318 and served as a parish priest in Brussels before moving to the hermitage of Groenendaal in 1343. He was a significant figure in medieval mysticism, known for his contemplative life and his efforts to address contemporary heresies through his writings. He composed his major works in Middle Dutch to reach a broader audience, rather than using the traditional Latin of the Church.