The accumulation of physical strength is most apparent in the increase of the human race. We have no trustworthy data for determining the population, even of any one civilised country, more than a century and a half ago; much less can we conjecture that of any country in primitive or prehistoric times. It is clear, however, that in prehistoric times--say, six or seven thousand years ago, there were very few men on the earth’s surface. The scarcity of food alone would be sufficient to prove that; and, indeed, all our data go to show it. Fifty years ago the world’s population used to be roughly conjectured at from seven to nine hundred millions, two-thirds of them in China and India. It is now estimated at over fifteen hundred millions. That of Europe alone must have tripled within a century, and can hardly be less than four hundred millions. That of North America may have scarcely exceeded four or five millions in the time of Christopher Columbus, or at the date of the first English settlements, though we have only the scantiest data for a guess. It may now be 130,000,000, for there are over a hundred millions in the United States alone, about fifteen in Mexico, and eight in Canada, besides the inhabitants of Central America. [Sidenote: The Prolific Power of White People] [Sidenote: Physical & Intellectual Power] The increase has been most swift in the civilised countries, such as Britain, Germany, Russia, and the United States; but it has gone on in India also since India came under British rule (famines notwithstanding), and in the regions recently colonised by Europeans, such as Australia, Siberia, and Argentina, the disappearance of aborigines being far more than compensated for by the prolific power of the white immigrants. Some regions, such as Asia Minor and parts of North Africa, are more thinly peopled now than they were under the Roman Empire, and both China and Peru may have no larger population than they had five, or ten, or fifteen centuries ago. But taking the world at large, the increase is enormous, and will apparently continue. Even after the vacant cultivable spaces which remain in the two Americas, Northern Asia, and Australasia have been filled, the discovery of new modes of enlarging the annually available stock of food may maintain the increase. It is most conspicuous among the European races, and is, of course, due to the greater production in some regions of food, and in others of commodities wherewith food can be purchased. It means an immense addition to the physical force of mankind in the aggregate, and to the possibilities of intellectual force also--a point to be considered later. And, of course, it also means an immense and growing preponderance of the civilised white nations, which are now probably one half of mankind, and may, in another century, when they have risen from about five hundred to, possibly, one thousand or fifteen hundred millions, be nearly two-thirds.