I should be glad if I could at once proceed to examine some of these groups of facts. But since the object which I have in view is not so much to lead you to any conclusions of my own, as to invite you to walk with me in comparatively untrodden paths, and to urge those of you who have leisure for historical investigations to explore them for yourselves more fully than I have been able to do—and since the main difficulties of the investigation lie less in the facts themselves than in the attitude of mind in which they are approached—I feel that I should fail of my purpose if I did not linger still upon the threshold to say something of the “personal equation” that we must make before we can become either accurate observers or impartial judges. There is the more reason for doing so, because the study of Christian history is no doubt discredited by the dissonance in the voices of its exponents. An ill-informed writer may state almost any propositions he pleases, with the certainty of finding listeners; a well-informed writer may state propositions which are as demonstrably true as any historical proposition can be, with the certainty of being contradicted. There is no court of appeal, nor will there be until more than one generation has been engaged upon the task to which I am inviting you. 1. In the first place, it is necessary to take account of the demand which the study makes upon the attention and the imagination of the student. The scientific, that is the accurate, study of history is comparatively new. The minute care which is required in the examination of the evidence for the facts, and the painful caution which is required in the forming of inferences, are but inadequately appreciated. The study requires not only attention, but also imagination. A student must have something analogous to the power of a dramatist before he can realize the scenery of a vanished age, or watch, as in a moving panorama, the series and sequence of its events. He must have that power in a still greater degree before he can so throw himself into a bygone time as to be able to enter into the motives of the actors, and to imagine how, having such and such a character, and surrounded by such and such circumstances, he would himself have thought and felt and acted. But the greatest demand that can be made upon either the attention or the imagination of a student is that which is made by such a problem as the present, which requires us to realize the attitude of mind, not of one man, but of a generation of men, to move with their movements, to float upon the current of their thoughts, and to pass with them from one attitude of mind into another.