[Sidenote:  Oceans and seas in universal history.]

The transformation of the ocean into a highway by the development of navigation is a late occurrence in the history of man and is perhaps the highest phase of his adaptation to environment, because an adaptation which has placed at his disposal that vast water area constituting three-fourths of the earth’s surface from which he had previously been excluded.  Moreover, it was adaptation to an alien and hostile element, whose violent displays of power recurrently stimulated the human adjustment between attack and defense.

Because adaptation to the sea has been vastly more difficult than to the land, commensurate with the harder struggle it has brought greater intellectual and material rewards.  This conquest of the sea is entitled to a peculiarly high place in history, because it has contributed to the union of the various peoples of the world, has formed a significant part of the history of man, whether that history is economic, social, political or intellectual.  Hence history has always staged its most dramatic acts upon the margin of seas and oceans; here always the plot thickens and gives promise of striking development.  Rome of the seven hills pales before England of the “Seven Seas.”

[Sidenote:  The sea in universal history.]

Universal history loses half its import, remains an aggregate of parts, fails to yield its significance as a whole, if it does not continually take into account the unifying factor of the seas.  Indeed, no history is entitled to the name of universal unless it includes a record of human movements and activities on the ocean, side by side with those on the land.  Our school text-books in geography present a deplorable hiatus, because they fail to make a definite study of the oceans over which man explores and colonizes and trades, as well as the land on which he plants and builds and sleeps.

The striking fact about the great World Ocean to-day is the manifold relations which it has established between the dwellers on its various coasts.  Marine cables, steamer and sailing routes combine to form a network of paths across the vast commons of the deep.  Over these the commercial, political, intellectual, or even purely migrant activities of human life move from continent to continent.  The distinctive value of the sea is that it promotes many-sided relations as opposed to the one-sided relation of the land.  France on her eastern frontier comes into contact with people of kindred stock, living under similar conditions of climate and soil to her own; on her maritime border she is open to intermittent intercourse with all continents and climes and races of the world.  To this sea border must be ascribed the share that France has taken in the history of North and South America, the West Indies, North and Equatorial Africa, India, China and the South Seas.  So we find the great maritime peoples of the world, from the Phoenicians to the English, each figuring in the history of the world of its day, and helping weave into a web of universal history the stories of its various parts.