The Greeks, quick and adventurous. skilled in mechanical art, had many of the qualities of successful navigators, and within the limits of their little inland sea ranged fearlessly and freely. But the conquests of Alexander did more to extend the limits of geographical science, and opened an acquaintance with the remote countries of the East. Yet the march of the conqueror is slow in comparison with the movements of the unencumbered traveller. The Romans were still less enterprising than the Greeks, were less commercial in their character. The contributions to geographical knowledge grew with the slow acquisitions of empire. But their system was centralizing in its tendency; and instead of taking an outward direction and looking abroad for discovery, every part of the vast imperial domain turned towards the capital at its head and central point of attraction. The Roman conqueror pursued his path by land, not by sea. But the water is the great highway between nations, the true element for the discoverer. The Romans were not a maritime people. At the close of their empire, geographical science could hardly be said to extend farther than to an acquaintance with Europe,--and this not its more northern division,--together with a portion of Asia and Africa; while they had no other conception of a world beyond the western waters than was to be gathered from the fortunate prediction of the poet.1 Then followed the Middle Ages; the dark ages, as they are called, though in their darkness were matured those seeds of knowledge, which, in fulness of time, were to spring up into new and more glorious forms of civilization. The organization of society became more favorable to geographical science. Instead of one overgrown, lethargic empire, oppressing every thing by its colossal weight, Europe was broken up into various independent communities, many of which, adopting liberal forms of government, felt all the impulses natural to freemen; and the petty republics on the Mediterranean and the Baltic sent forth their swarms of seamen in a profitable commerce, that knit together the different countries scattered along the great European waters.