JOHN ARNDT, was a famous Protestant theologian of the 16th century, and may be regarded as the founder of the German Pietism of a later generation. He was born at Ballenstädt, in Anhalt, in 1555, and studied in a variety of universities—in Helmstädt in 1576 ; in Wittenberg in 1577, when the crypto-Calvinist controversy was at its height, and where he took the side of Melanchthon and the crypto-Calvinists; in Strasburg, under Pappus, who was a strict Lutheran and had a great influence over him; in Basel, where he studied theology under Sulcer, and also medicine. In 1581 he went back to Ballenstädt, but was soon recalled to active life by his appointment to the pas-torate at Badeborn in 1583. After some time his Lutheran tendencies exposed him to the anger of the authorities, who were of the Reformed church. He found an asylum in Quedlinburg, and afterwards was transferred to St Martin's church in Brunswick. Arndt's fame rests on his writings, which were mainly of a mystical devotional kind, and were inspired by Bernard, Tauler, and Thomas k Kempis. His principal work is The True Christianity, which has been translated into most European languages, and has served as the foundation of many devotional works, both Roman Catholic and Protestant. In this book Arndt dwells upon the mystical union between the believer and Christ, and his aim is to correct the purely forensic side of the Reformation theology, which paid almost exclusive attention to Christ's death for His people, by drawing attention to Christ's life in His people. Like Luther, Arndt was very fond of the little anonymous book, Deutsche Theologie, and published an edition with a preface recommending it. The first edition of his True Christianity appeared in 1605. His other works are The Death of Adam and the Life of Christ, Thoughts on various Books of the Bible, The House and the Heart Church, Soul Medicine for the Pestilence, and De Unione Credentium cum Christo. His True Christianity has been translated into English at least twice, and has gone through a great number of editions; the best known translation is that of A. W. Boehm, Lond. 1720. Several of his sermons are published in R. Nesselmann's Buch der Predigten, 1858. Arndt has always been held in very high repute by the German Pietists, and the founders of Pietism, Spener and Storr, repeatedly call attention to him and his writings ; they have gone so far as to compare him to Plato, cf. C. Scheele, Plato und Johan Arndt, Ein Vortrag, die., 1857. A valuable account of Arndt is to be found in C. Asch-mann's Essai sur la Vie, etc., de J. Arndt. (T. M. L.)