Until recently, the surface of the soil was a far more important source of wealth than was that which lies beneath the surface. There were iron mines among the Chalybes on the Asiatic coast of the Euxine in ancient times; there were silver mines here and there, the most famous being those at Laurium, from which the Athenians drew large revenues, gold mines in Spain and Dacia, copper mines in Elba, tin mines in the south-west corner of Britain. But the number of persons employed in mining and the industries connected therewith was relatively small both in the ancient world and, indeed, down till the close of the eighteenth century. The immense development of coal-mining and of iron-working in connection therewith has now doubled, trebled, or quadrupled the population of large areas in Britain, Germany, France, Belgium, and the United States, adding vastly to the wealth of these countries and stimulating in them the growth of many mechanical arts. This new population is quite different in character from the agricultural peasantry who in earlier days formed the principal substratum of society. Its appearance has changed the internal politics of these countries, disturbing the old balance of forces and accelerating the progress of democratic principles. [Illustration: THE PLACE OF MOUNTAINS IN HISTORY: NATURE’S BARRIERS TO MAN’S EXPANSION Without the Alps the annals of Europe must have been entirely different. The mountains were too much for the emperors of the Middle Ages, although Hannibal, the great Carthaginian general, succeeded in crossing them two centuries before Christ, a feat which Napoleon repeated 2,000 years later. Our engraving illustrates Napoleon crossing the Alps. ] Nor have minerals failed to affect the international relations of peoples and States. It was chiefly for the precious metals that the Spaniards explored the American Continent and conquered Mexico and Peru. It was for the sake of capturing the ships bringing those metals back to Europe that the English sea-rovers made their way to the American coasts and involved England in wars with Spain. It was the discovery in 1885 of extensive auriferous strata unexampled in the certainty of their yield that drew a swarm of foreign immigrants into the Transvaal, whence arose those difficulties between them and the Dutch inhabitants previously established there which, coupled with the action of the wealthy owners of the mines, led at last to the war of 1899 between Britain and the two South African Republics. [Sidenote: Man’s Fight with Nature]