Hans Urs von Balthasar (1905-88), a Swiss theologian and priest, is considered by many the most important Catholic theologian of the twentieth century. Incredibly prolific and diverse, he wrote over one hundred books and many hundreds of articles. A favorite theologian and spiritual writer of Pope Francis, as well as the two previous Popes, he was called "the most cultured man of our time" by Henri de Lubac, and Karl Rahner described his achievements as "really breathtaking."