1895-1964. Dutch Calvinist writer. Educated at the Free University and at Erlangen, he was early attracted by the field of religious psychology. In 1921 he went to the Dutch East Indies and, apart from a pastorate in the Netherlands (1926-29), spent the next two decades there, increasingly involved in mission work and writing extensively. In 1939 he became professor of missions at Kampen and at the Free University; worked in the anti-Nazi underground during World War II; and thereafter resumed his teaching and writing career. He founded the Calvinist (Gereformeerde Kerk) center for missions at Baarn. His best-known work is Inleiding in de Zendingswetenschap (1954), translated as An Introduction to the Science of Missions (1960). Other writings deal with religious consciousness, mysticism, and related topics.