On the heresy of Pelagianism cfr. *F. Wörter, _Der Pelagianismus nach seinem Ursprung und seiner Lehre_, Freiburg 1874.—F. Klasen, _Die innere Entwicklung des Pelagianismus_, Freiburg 1882.—Schwane, _Dogmengeschichte_, Vol. II, 2nd ed., § 60 sqq., Freiburg 1895.—H. Zimmer, _Pelagius in Irland_, Berlin 1901.—Warfield, _Two Studies in the History of Doctrine_, New York 1897.—Tixeront, _Histoire des Dogmes_, Vol. II, 2nd ed., Paris 1909 (English tr., St. Louis 1914).—Pohle in the _Catholic Encyclopedia_, Vol. XI, pp. 604-608.—B. J. Otten, S. J., _A Manual of the History of Dogmas_, Vol. I, pp. 357 sqq. On Semi-Pelagianism cfr. Suarez, _De Gratia_, Prolegom., V, 5 sqq.—Livinus Meyer, _De Pelag. et Semipelag. Erroribus._—Wiggers, _Geschichte des Semipelagianismus_, Hamburg 1835.—A. Hoch, _Lehre des Johannes Cassianus von Natur und Gnade_, Freiburg 1895.—*A. Koch, _Der hl. Faustus, Bischof von Riez_, Stuttgart 1895.—Fr. Wörter, _Zur Dogmengeschichte des Semipelagianismus_, Münster 1900.—Sublet, _Le Semipélagianisme_, Namur 1897.—Tixeront, _Histoire des Dogmes_, Vol. II, 2nd ed., Paris 1909 (English tr., St. Louis 1914).—Pohle in the _Catholic Encyclopedia_, Vol. XIII, pp. 703-706.—B. J. Otten, S. J., _A Manual of the History of Dogmas_, Vol. I, pp. 379 sqq. On Jansenism cfr. *Steph. Dechamps, _De Haeresi Ianseniana_, Paris 1645.—Ripalda, _De Ente Supernaturali_, Vol. III: “Contra Baium et Baianos,” Cologne 1648.—Duchesne, _Histoire du Baianisme_, Douai 1731.—*Linsenmann, _Michael Bajus und die Grundlegung des Jansenismus_, Tübingen 1867.—A. Schill, _Die Konstitution Unigenitus, ihre Veranlassung und ihre Folgen_, Freiburg 1876.—Ingold, _Rome et France: La Seconde Phase du Jansénisme_, Paris 1901.—P. Minges, O. F. M., _Die Gnadenlehre des Duns Scotus auf ihren angeblichen Pelagianismus und Semipelagianismus geprüft_, Münster 1906.—Lafiteau, _Histoire de la Constitution Unigenitus_, 2 vols., Liège 1738.—Van den Peereboom, _Cornelius Jansenius, Septième Évêque d’Ypres_, Bruges 1882.—J. Forget in the _Catholic Encyclopedia_, Vol. VIII, pp. 285-294.—B. J. Otten, S. J., _A Manual of the History of Dogmas_, Vol. II, pp. 507 sqq. Section 2. The Gratuity Of Actual Grace All grace _ex vi termini_ is a free gift.(406) This applies particularly to Christian grace, which is so absolutely gratuitous that its gratuity, together with its necessity, may be called the groundwork of the Catholic religion. 1. STATE OF THE QUESTION.—To show what is meant by “gratuity” (_gratuitas_) we must first explain the technical term “merit.” a) “Merit” (_meritum_=that which is earned) is that property of a good work which entitles the performer to receive a reward from him to whose advantage the work redounds.