Romano Guardini (1885-1968) was ordained priest in 1910. He served in Mainz and dedicated much of his life to working with the young. He received his doctorate in theology in 1915, writing on the theology of St. Bonaventure, and taught for most of his career at the University of Berlin as Professor of Catholic Philosophy. His noteworthy books include Sacred Signs (1917), The Spirit of the Liturgy (1918), Liturgical Formation (1923), The Lord (1937), and The End of the Modern World (1956).