In a former chapter I have told you how the idea of the Roman Empire continued to live for a thousand years after the death of the last Roman Emperor. It caused the establishment of a large number of “imitation empires.” It gave the Bishops of Rome a chance to make themselves the head of the entire church, because they represented the idea of Roman world-supremacy. It drove a number of perfectly harmless barbarian chieftains into a career of crime and endless warfare because they were for ever under the spell of this magic word “Rome.” All these people, Popes, Emperors and plain fighting men were not very different from you or me. But they lived in a world where the Roman tradition was a vital issue—something living—something which was remembered clearly both by the father and the son and the grandson. And so they struggled and sacrificed themselves for a cause which to-day would not find a dozen recruits. In still another chapter I have told you how the great religious wars took place more than a century after the first open act of the Reformation and if you will compare the chapter on the Thirty Years War with that on Inventions, you will see that this ghastly butchery took place at a time when the first clumsy steam engines were already puffing in the laboratories of a number of French and German and English scientists. But the world at large took no interest in these strange contraptions, and went on with a grand theological discussion which to-day causes yawns, but no anger. And so it goes. A thousand years from now, the historian will use the same words about Europe of the out-going nineteenth century, and he will see how men were engaged upon terrific nationalistic struggles while the laboratories all around them were filled with serious folk who cared not one whit for politics as long as they could force nature to surrender a few more of her million secrets. You will gradually begin to understand what I am driving at. The engineer and the scientist and the chemist, within a single generation, filled Europe and America and Asia with their vast machines, with their telegraphs, their flying machines, their coal-tar products. They created a new world in which time and space were reduced to complete insignificance. They invented new products and they made these so cheap that almost every one could buy them. I have told you all this before but it certainly will bear repeating.