Jansenius (Jansen), Cornelius, a Dutch theologian, born at Akoi, near Leerdam, Oct. 28, 1585, died in Ypres, May 6,1638. He studied theology at the university of Louvain, which unwaveringly adhered to the Augustinian system of Baius (died 1589), though 76 propositions of it had been condemned in 1567 by the see of Rome. After studying and teaching at Paris and Bayonne, he became in 1617 president of the Pulcheria college at Louvain, where he lectured on theology, and in 1630 professor of theology at the university. In 1635 he was made bishop of Ypres. The writings of Augustine against the Pelagians he read 30 times, and his other writings 10, times. , Like Baius he adopted the Augustinian doctrine of grace in its strictest sense, and was therefore opposed to the theological views of the Jesuits, whom he prevented from lecturing at Louvain on philosophy. He believed that the Catholic church of his time had in this and in other points departed from the doctrines of the old church, and therefore in 1621 projected, with his friend Duvergier de Hauranne, abbot of St. Cyran, the plan of a reformation, Jansenius taking the doctrine and St. Cyran the constitution and the religious life as their respective fields of labor.

Irish clergymen of high standing and the heads of the French Oratorians favored this plan. In spite of the violent opposition of the Jesuits and the inquisition, he was sustained throughout his controversies by the Spanish government; and he confirmed his influence at Madrid by twice visiting that city (1624-5). Jansenius commenced his work on the doctrine of Augustine in 1627, and had hardly finished it when he died. On his deathbed he recommended to his friends its publication, which the Jesuits and the papal nuncio at Cologne, anticipating the renewal of a violent controversy, strove to prevent. It appeared (3 vols, fol.), under the auspices of the university, and the editorial care of Liberus Froidmont and Ka-len, in 1640, with the title Augustinus, seu Doctrina Augustini de Humana Naturae Sanitate, AEgritudine et Medicina, adversus Pela-gianos et Massilienses, and was soon reprinted at Paris (1641) and Rouen (1643). The work sets forth the Augustinian doctrine of irresistible grace and absolute election or rejection, mostly in the words of Augustine; it rejects the use of reason in religious questions, designates philosophy as the mother of all heresy, defends Baius, and accuses the Jesuits in general, and in particular Fonseca, Lessius, Molina, and others, of semi-Pelagianism. The Jesuits attacked the work as repeating the condemned propositions of Baius, and Urban VIII. in 1642 condemned it as heretical by the bull In eminenti, and placed it on the prohibitory index. - The name Jansenists is commonly applied to those Christians who, in France particularly, considered the opinions of Jansenius the true doctrine of the Catholic church, notwithstanding their condemnation by all the popes since 1642. In Holland, where they always maintained their hierarchical organization in spite of the censures of the Roman see, they called themselves the Old Episcopal or Old Catholic church, a designation which has recently been adopted also in some parts of Germany. The friends of Jansenius in the Netherlands, among whom were several bishops and nearly all the professors of the universities, submitted after some hesitation to the bull In eminenti in 1647. A greater resistance was made in France, where St. Cyran, An-toine Arnauld, his sister Ange1ique, the abbess of the Cistercian convent of Port Royal, Pascal, and a community of scholars who lived in the manner of the ancient anchorets in the vicinity of Port Royal des Champs (messieurs de Port Royal des Champs), took their stand in favor of Jansenius. When Innocent X. in 1653 denounced five propositions in the works of Jansenius as heretical, a majority of the Jansenists denied that these propositions had been understood by the author in the sense in which they were condemned.

Alexander VII., however, in 1656 demanded of the French clergy a declaration by which they should reject the condemned propositions as propositions of Jansenius. This raised the question, whether the pope's admitted infallibility in matters of faith extended also to historical facts. Louis XIV. lent his support to the execution of this as well as other measures of the popes against Jansenism, declaring at a national assembly of the French clergy in 1660 that he regarded it as his religious duty to exterminate Jansenism: Clement IX. in 1668 endeavored to put a stop to the controversy by a decree (Pax Clementina), which demanded merely a rejection of the five propositions, without ascribing them to Jansenius. (La paix de Clement IX., Brussels, 1701. The author, who is not named on the title page, was Quesnel, who died in 1719.) But Clement XL and Louis XIV. soon had recourse to severer measures; many Jansenists fled to the Netherlands, and Port Royal was suppressed in 1709. The controversy had broken out with new violence on the publication of Quesnel's celebrated work on the New Testament (Le Nouveau Testament en frangais, avec des reflexions morales). Clement XL, by the constitution Unigenitus (1713), condemned 101 propositions of this book as heretical, dangerous, or offensive to pious ears.

A large portion of the French clergy and people, with the archbishop of Paris, the cardinal de Noailles, at their head, publicly resisted the constitution, and were therefore called Anticonstitutionalists. A papal decree of Sept. 2, 1718, threatened with excommunication all who would not submit unconditionally. Many yielded, among them Cardinal Noailles, but four bishops (those of Mirepoix, Montpellier, Boulogne, and Senez) appealed to an oecumenical council. Those who sustained this appeal, among whom were many opposed to Jansenism, were called Appellants. The parliament perseveringly resisted the decrees against Jansenism; the Sorbonne wavered, and when pressed generally submitted to the papal decrees. Some of the bishops continued to patronize it, and the general chapter of the Oratorians resolved in 1727 not to accept the bull Unigenitus. A popular saint, Francis of Paris, died with the appeal in his hand (1727), and the miracles and wild convulsions which were reported to have taken place at his grave made a deep impression on large classes of the people.

But when the constitution by an act of royal sovereignty had been enforced as a law of the kingdom (1730), the resistance of the Jansenists was gradually overcome, and the Oratorians accepted the bull in 1746. New difficulties arose for a while when Beaumont, archbishop of Paris, in 1752, ordered the sacraments to be refused to all who had not accepted the constitution; but in 1756 peace was restored by means of a mild pastoral letter from Benedict XIV. The Jansenist party remained very strong among the French clergy, and most of the clerical deputies in the states general of 1789 belonged to it. After the restoration also it found many advocates among the clergy and laity, and since 1854 has had an organ in the religious press (L' Observateur Ca-tholique). In Italy several bishops who were in favor of the reforms of Leopold I. of Tuscany and of Napoleon, as Ricci, bishop of Pis-toja, and Capece-Latro, archbishop of Taranto, were regarded as Jansenists. - While Jansenism remained in France a theological school, it became in the Netherlands an independent church. In 1704 Codde, the vicar apostolic of the archbishopric of Utrecht, was deposed by the pope for holding Jansenistic views, but the chapter refused to acknowledge the validity of this deposition.

In 1723 the chapter chose an archbishop of Utrecht, who was consecrated by the bishop of Babylon, a French bishop in partibus, who lived as a fugitive at Amsterdam. The pope was informed of the election, but answered by a condemnatory brief. The archbishop appealed from the condemnation of the pope to the next general council, a step which has since been taken by each of his successors. The next archbishop, Barchman Wuytiers, received letters of communion from many bishops, more than 100 of which are preserved in the archives of the church of Utrecht. After the death of the bishop of Babylon, Archbishop Meindaarts (elected in 1739) restored the suffragan see of Haarlem in 1742, and that of De-venter in 1758, in order to secure a succession of prelates. In 1856 the bishops of the Jansenist church jointly protested against the doctrine of the immaculate conception. They took an active interest in the rise and progress of the Old Catholic movement in Germany. By invitation the archbishop of Utrecht in 1872 administered the sacrament of confirmation in a number of Old Catholic congregations of Germany, and in 1873 the bishop of Deventer, then the only surviving bishop of the Jansenists, consecrated the first Old Catholic bishop for Germany. The Jansenist church in 1873 had 25 congregations and 25 pastors, all in the dioceses of Utrecht and Haarlem, the diocese of Deventer having no congregation.

In 1874 the Jansenist church of Utrecht, numbering about 5,000 members, formally joined the Old Catholics. - See Leydecker, Historia Jansenismi (Utrecht, 1695); Lucchesini, Historia Polemica Jansenismi (3 vols., Rome, 1711); Tregelles, "The Jansenists" (London, 1851); and the Rev. J. M. Neale, "History of the so-called Jansenist Church of Holland " (Oxford, 1858).