In this essay I do not aspire to recount the narrative of the empire, or to instruct trained historians. Nor do I propose to trace the history of the imperial idea, which Mr. Bryce has exhibited in a work which it would be impertinence in me to commend. My object is to examine the working of the imperial idea during that portion of medieval history when, having assumed a definite theological shape, it operated as a powerful influence over the destinies of Germany and Italy. I wish to see how the machine of imperial government worked in these countries from the revival of the empire by Otto I. to the downfall of the Hohenstauffen dynasty. It seemed, however, necessary by way of introduction to explain why the empire survived at all, and why it was revived in 962.