The problem of simplifying and of unifying the material for study so as to give the student a clear conception of the course of European development is one that confronts the teacher at every turn and calls constantly for solution. In this connection Professor Emerton, in his address on the “Teaching of Medieval History in the Schools,” points out the importance of the study of the Church as the great unifying element in European progress, especially throughout the Middle Ages. “All the peoples of Europe, divided as they are by nationalities and by social classes, are all united in this one common possession of religion and a culture derived from Rome and holding them still after generations of separation in an ideal attachment to something they feel to be higher and better than anything in their present world.” The aims of the papacy in particular, says Professor Emerton, make this task of the teacher easier of solution, because the successors of St. Peter, even harking back to the times of Gregory I, strove one and all for the same end--“to enforce anew this ideal of a vast Christian State, governed in the last resort by an appeal to its own divinely-constituted tribunal.” The greatest efforts put forth to this end fall within the period under consideration, namely from the times of Hildebrand to the death of Frederick II, or, more exactly, from about 1050, when Hildebrand was fast becoming the power behind the papal throne, to 1268, when Conradin’s untimely death in the market place of Naples terminated the rule of the Hohenstaufen. The presentation of the relations between the popes and the emperors of this period involves a fourfold task, namely an appreciation (1) of the time covered and the areas concerned, (2) the personalities involved, (3) the issues at stake, and (4) the effects of the struggle on Europe. The Elements of Time and Place. It may be an elementary consideration, but it is withal fundamental, that the pupil grasp the length of time involved, the order in which the events occurred, and the theater on which they transpired. It is not a continuous struggle, for it is opened, then closed, then reopened again; now by pope, now by emperor. On the other hand these successive meetings of popes and emperors in conflict are but phases of one and the same great struggle for supremacy, whose issue Professor Emerton has so clearly stated. These phases must be clearly defined as to their time limits if the student is to follow the contest intelligently. As to the countries or localities involved he must understand what was meant by the Holy Roman Empire of the German people and what its limits were, both actual and theoretical; to which he must add a more detailed knowledge of Italy, particularly of Lombardy and the new Norman kingdom in the South, which proved to be such an important factor in the situation. The Personalities in the Struggle.