So far as the Papacy was concerned the Holy Roman Empire created a rival world-ruler with whom for five hundred years the Popes were in almost endless strife. Under powerful rulers like Otto the Great the Papacy was subjected to the Empire more absolutely than in the day of Charles the Great. Under the great German Emperors much was done to reform the Church and to advance its interests and influence in the world. Each Emperor took a coronation oath to defend and protect the Church against heretics, schismatics, infidels, pagans, and all other enemies, and that obligation was as a rule faithfully and loyally kept. But all things considered was the Papacy stronger or weaker, better or worse, for the creation of the Holy Roman Empire? Does the fact that the Papacy declined with the decay and death of the Empire suggest a necessary dependence of the former on the latter? SOURCES A.--PRIMARY: I.--IN ENGLISH: The materials available in English are scarce and very unsatisfactory. A few documents will be found in the following: 1.--Balzani, U., _Early Chronicles of Italy_. Lond., 1883. 2.--Henderson, _Select Historical Documents of the Middle Ages_. 3.--Ogg, _Source Book of Mediæval History_. 4.--Robinson, _Readings in European History_, i., ch. 12. 5.--Thatcher and McNeal, _A Source Book for Mediæval History_. 6.--Univ. of Penn., _Translations and Reprints_. II.--IN FOREIGN LANGUAGES: The primary sources not in English are very extensive.[415:1] The chief collections are: 1.--Altmann, W., and Bernheim, E., _Ausgewählte Urkunden zur Erläuterung der Verfassungsgeschichte Deutschlands im Mittelalter_. Berl., 1891. 2.--Baronius, _Annales_, vols. xiii.-xix. Luca, 1738. 35 vols. 3.--Boehmer, J. F., _Fontes rerum Germanicarum_. Stuttg., 1843-68. 4 vols. 4.--_Die Geschichtsschreiber der deutschen Vorzeit._ 2d ed. Berl. and Leipz., 1885 _sqq._ 90 vols. 5.--Doeberl, M., _Monumenta Germaniæ selecta ab a. 768 usque ad a. 1250_. Munch., 1889-90. 6.--Jaffé, P., _Bibliotheca rerum Germanicarum_. Berl., 1864-73. 6 vols. _Regesta Pontificum Romanum_ (to 1198). Berl. 1851. 7.--Lehmann, H. O., _Quellen zur Deutschen Reichs-und Rechtsgeschichte_. Berl., 1891. 8.--Mansi, _Sacrorum Conciliorum Collectio_, xviii. 9.--Migne, vol. 142. Glaber, _Historia sui temporis_. 10.--Mirbt, _Quellen zur Geschichte des Papsttum_. 11.--Muratori, _Rerum Italicarum Scriptores_. Med., 1723-51. 28 vols. 12.--Pertz, et al., _Monumenta Germania Historica_, 1826 _ff._ 13.--Pflugh-Harttung, _Acta Pontificum Romanorum_. Tub., 1881-8. 3 vols. 14.--_Scriptores rerum Germanicarum in usum Scholarum._ Hanover, 1840 ff. 42 vols.