Primary sources for the settlement of the canon law on the subject of divorce are the _Decretum_ of Gratian and the other materials comprised in Richter-Friedberg's _Corpus juris canonici_. For England Johnson's _Canons_ and Godolphin's _Repartorium canonicum_ (3d ed., London, 1687) are serviceable. The state of the law in the age of the decretalists may be learned from Wunderlich's edition of Tancred's _Summa de matrimonio_ (Göttingen, 1841); and for its historical development the great works of Esmein and Freisen, elsewhere mentioned, are indispensable. Schulte's _Lehrbuch_ and the _Lehrbuch_ of Friedberg cover the subject. In connection with the rise of the jurisdiction of the church should be read Sohm, "Die geist. Gerichtsbarkeit im frank. Reich," in _ZKR._, IX (Tübingen, 1870). For the matrimonial experiences of Margaret of Scotland, illustrating the facility of divorce by indirect methods under the canon law, see Tait's article in the _Dict. of Nat. Biog._, XXXVI; and similar material in the _Reports of the Historical Manuscripts Commission_. For the literature relating to the Council of Trent consult Bibliographical Note VII. The foundation of the Protestant doctrine of divorce was laid by Martin Luther. His writings on the subject may, of course, be found in his collected works mentioned in Bibliographical Note IX; or in the source-book of Strampff, _Luther: Ueber die Ehe_ (Berlin, 1857); while the more important papers are reprinted in Vol. II of the _Kleinere Schriften Dr. Martin Luthers: von Ehe- und Klostersachen_ (Bielefeld and Leipzig, 1877). An earlier book of a somewhat similar character is Froböse's _Dr. Martin Luther's ernste, kräftige Worte über Ehe und eheliche Verhältnisse_ (Hanover, 1825). In the sixteenth century Luther's relatively conservative teaching regarding the scriptural grounds of divorce is adopted in the main by the theologians Brenz, _Wie yn Ehesachen ... zu Handeln_ (1530); Bugenhagen, _Von Ehebruch und Weglaufen_ (1539); also in the collections of Sarcerius, below mentioned; Chemnitz, _Examen concilii tridentini_ (Frankfort, 1615); Beza, _Tractatio de repudiis et divortiis_ (Geneva, 1569); the jurists Kling, _Matrimonialium causarum tractatus_ (1st ed., Frankfort, 1553; 3d ed., here cited, 1577), being a reprint of the title "De nuptiis" of his _Enarrationes in Institutiones_ (1542); Beust, _Tractatus de jure connubiorum_ (3d ed., Leipzig, 1592); _idem_, _Tractatus de sponsalibus et matrimoniis_ (Wittenberg, 1586); Schneidewin, _Commentarius in Institutiones_ (1st ed., Wittenberg, 1571); and _idem_, _De nuptiis_ (Jena, 1585), being a part of the earlier work published by the heirs after the author's death. In the seventeenth century the more stringent tendency is represented