I. Jean, a French theologian, born in Bayonne in 1581, died in Paris, Oct. 11, 1643. He was educated in theology at Louvain, where Jansenius was at the same time a student, with whom he formed an intimate friendship, and who accompanied him to Bayonne, but soon returned. Duvergier was appointed canon of Bayonne, and afterward of Poitiers and abbot of St. Cyran. His rigor and zeal becoming known, he was invited to Paris, where he made numerous disciples in all classes of society. He refused several bishoprics. His Jansenist principles brought upon him the enmity of the Jesuits, and in 1638 he was imprisoned at Vincennes by order of Richelieu, after whose death he was released, but did not long survive. His most celebrated writings are those which he directed against the Jesuit Garasse. Pascal, Arnauld, and Nicole were his disciples. II. Prosper, a French politician and author, descended from a brother of the preceding, born in Rouen, Aug. 3, 1798. He was for many years associated as a journalist with Guizot, Remusat, and Rossi. In 1831 he was chosen to the chamber of deputies from Sancerre, and at first gave his support to the government of Louis Philippe, but became one of the prominent champions of reform.

After the revolution of 1848 he represented the department of Cher in the constituent assembly, and in November, 1850, became a member of the legislative assembly. After the coup d'etat of 1851 he was imprisoned, and then banished until August, 1852. His principal work is the His-toire du gouvernement parlementaire en France (7 vols., Paris, 1857-65). He was elected a member of the academy in 1870.