The growth of knowledge is a symptom not only of the collective capacity of living man but also of the continuity of the present age with those which had laid the earlier foundations. One school of vigorous action, and still more vigorous talk, advises our generation to be done with the past and make a fresh start on more ideal lines. This is not the voice of science, which, just in proportion to its growth, has shown more and more care for its origins and its past: and this is true at every stage in the history of thought. The Greeks, fighting for freedom and establishing in the city-state a new form of political organization for the world, were yet in their scientific evolution true and grateful successors of the priests who first compiled the observations necessary for the scientific study of the heavens and founded the art of medicine. The men of the Renascence, who were burnt and imprisoned for doubting the verbal inspiration of Aristotle and the Bible, were in fact going back to an earlier impulse than that of the scholastic philosophy. The mathematics of Pappus and the mechanics of Archimedes had to be carried further before the new sciences of which Aristotle had given the first sketch could be securely founded. The pioneers of the sixteenth and seventeenth centuries built therefore on the past, although accused of impiety and revolution; and it must be so with any intellectual construction which is to hold its own and form the future. So far from there being any opposition in nature between history and science, the two are but different aspects of one continuous enlargement of the human spirit, which sees and lives more fully at each great moment of its progress, and, so far as it is alive, is always informed by the real achievements of the past. We illustrate this advance in the marvellous record of our fifth chapter, and its spirit is summed up in the great saying of Benedetto Croce that 'all history is contemporary history'. But the reader may here begin not unnaturally to feel some impatience with the argument, and to think that he is being carried into a region of ideal imaginings quite out of touch with the realities of blood and hatred and starvation with which we have been actually surrounded at the end of our period. It is well to be thus sharply reminded of the contrariety of facts, when we are sailing smoothly along on the current of any theory, whether of education or politics, religion or art. To get right with our objector, to set our sail so that the rocks in the stream may not completely wreck us, we will go back to the point where we were insisting on the obvious truth that the collective resources and capacity of mankind have of late enormously increased.