Successive maritime periods in history.
Growth demands space. Therefore, the progress of history has been attended by an advance from smaller to larger marine areas, with a constant increase in those manifold relations between peoples and lands which the water is able to establish. Every great epoch of history has had its own sea, and every succeeding epoch has enlarged its maritime field. The Greek had the Aegean, the Roman the whole Mediterranean, to which the Middle Ages made an addition in the North Sea and Baltic. The modern period has had the Atlantic, and the twentieth century is now entering upon the final epoch of the World Ocean. The gradual inclusion of this World Ocean in the widened scope of history has been due to the expansion of European peoples, who, for the past twenty centuries, have been the most far-reaching agents in the making of universal history. Owing to the location and structure of their continent, they have always found the larger outlet in a western sea. In the south the field widened from the Phoenician Sea to the Aegean, then to the Mediterranean, on to the Atlantic, and across it to its western shores; in the north it moved from the quiet Baltic to the tide-swept North Sea and across the North Atlantic. Only the South Atlantic brought European ships to the great world highway of the South Seas, and gave them the choice of an eastern or western route to the Pacific. Every new voyage in the age of discovery expanded the historical horizon; and every improvement in the technique of navigation has helped to eliminate distance and reduced intercourse on the World Ocean to the time-scale of the ancient Mediterranean.
It would be a mistake, however, to suppose that the larger oceanic horizon has meant a corresponding increase in the relative content and importance of history for the known world of each period. Such an intense, concentrated national life as occurred in those little Mediterranean countries in ancient times is not duplicated now, unless we find a parallel in Japan's recent career in the Yellow Sea basin. There was something as cosmic in the colonial ventures of the Greeks to the wind-swept shores of the Crimea or barbarous wilds of Massilia, as in the establishment of English settlements on the brimming rivers of Virginia or the torrid coast of Malacca. Alexander's conquest of the Asiatic rim of the Mediterranean and Rome's political unification of the basin had a significance for ancient times comparable with the Russification of northern Asia and the establishment of the British Empire for our day.
The ocean has always performed one function in the evolution of history; it has provided the outlet for the exercise of redundant national powers. The abundance of opportunity which it presents to these disengaged energies depends upon the size, location and other geographic conditions of the bordering lands. These opportunities are limited in an enclosed basin, larger in the oceans, and largest in the northern halves of the oceans, owing to the widening of all land-masses towards the north and the consequent contraction of the oceans and seas in the same latitudes.
Contrasted historical rôthe Baltic played theles of northern and southern hemispheres.
A result of this grouping is the abundance of land in the northern hemisphere, and the vast predominance of water in the southern, by reason of which these two hemispheres have each assumed a distinct rôle in history. The northern hemisphere offers the largest advantages for the habitation of man, and significantly enough, contains a population five times that of the southern hemisphere. The latter, on the other hand, with its vast, unbroken water areas, has been the great oceanic highway for circum-mundane exploration and trade. This great water girdle of the South Seas had to be discovered before the spherical form of the earth could be proven. In the wide territory of the northern hemisphere civilization has experienced an uninterrupted development, first in the Old World, because this offered in its large area north of the equator the fundamental conditions for rapid evolution; then it was transplanted with greatest success to North America. The northern hemisphere contains, therefore, "the zone of greatest historical density," from which the track of the South Seas is inconveniently remote. Hence we find in recent decades a reversion to the old east-west path along the southern rim of Eurasia, now perfected by the Suez Canal, and to be extended in the near future around the world by the union of the Pacific with the Caribbean Sea at Panama; so that finally the northern hemisphere will have its own circum-mundane waterway, along the line of greatest intercontinental intercourse.
Size of the oceans
The size of the ocean as a whole is so enormous, and yet its various subdivisions are so uniform in their physical aspect, that their differences of size produce less conspicuous historical effects than their diversity of area would lead one to expect. A voyage across the 177,000 square miles (453,500 square kilometers) of the Black Sea does not differ materially from one across the 979,000 square miles (2,509,500 square kilometers) of the Mediterranean; or a voyage across the 213,000 square miles (547,600 square kilometers) of the North Sea, from one across the three-hundredfold larger area of the Pacific. The ocean does not, like the land, wear upon its surface the evidences and effects of its size; it wraps itself in the same garment of blue waves or sullen swell, wherever it appears; but the outward cloak of the land varies from zone to zone. The significant anthropo-geographical influence of the size of the oceans, as opposed to that of the smaller seas, comes from the larger circle of lands which the former open to maritime enterprise. For primitive navigation, when the sailor crept from headland to headland and from island to island, the small enclosed basin with its close-hugging shores did indeed offer the best conditions. To-day, only the great tonnage of ocean-going vessels may reflect in some degree the vast areas they traverse between continent and continent. Coasting craft and ships designed for local traffic in enclosed seas are in general smaller, as in the Baltic, though the enormous commerce of the Great Lakes, which constitute in effect an inland sea, demands immense vessels.