In the beginning of history, according to received authority, there was but a little tract of the earth occupied, and that by one family, speaking but one tongue, and worshipping but one God,--all the rest of the world being an uninhabited wild. At _this_ stage of history the whole globe is explored, covered with races of every color, a host of nations and languages, with every diversity of custom, development of character, and form of religion. The physical bound from that to this is equalled only by the leap which the world of mind has made. Once upon a time a man hollowed a tree, and, launching it upon the water, found that it would bear him up. After this a few little floats, creeping cautiously near the land, were all on which men were wont to venture. _Now_ there are sails fluttering on every sea, prodigious steamers throbbing like leviathans against wind and wave; harbors are built, and rocks and shoals removed; lighthouses gleam nightly from ten thousand stations on the shore; the great deep itself is sounded by plummet and diving-bell; the submarine world is disclosed; and man is gathering into his hands the laws of the very winds that toss its surface. Once the earth had a single rude, mud-built hamlet, in which human dwellings were first clustered together. _Now_ it is studded with splendid cities, strewn thick with towns and villages, diversified by infinite varieties of architecture: sumptuous buildings, unlike in every clime, each as if sprung from its own soil and made out of its air. Once there were only the elementary discoveries of the lever, the wedge, the bended bow, the wheel; Tubal worked in iron and copper, and Naamah twisted threads. Since then what a jump the mechanical arts have made! These primitive elements are now so intricately combined that we can hardly recognize them; new forces have been added, new principles evolved; ponderous engines, like moving mountains of iron, shake the very earth; many-windowed factories, filled with complex machinery driven by water or its vapor, clatter night and day, weaving the plain garments of the poor man and the rich robes of the prince, the curtains of the cottage and the upholstery of the palace.