Of the part which the great bodies of water have played, of the significance in the oceans of mighty currents like the Gulf Stream, the Polar Current, the Japan Current, the Mozambique Current, it would be impossible to speak within reasonable compass. But two remarks may be made before leaving this part of the subject. One is that man’s action in cutting through an isthmus may completely alter the conditions as given by Nature. The Suez Canal has of late years immensely enhanced the importance of the Mediterranean, already in some degree restored by the decay of Turkish power, by the industrial revival of Italy, and by the French conquests in North Africa. The cutting of a canal at Panama will change the relations of the seafaring and fleet-owning nations that are interested in the Atlantic and the Pacific. And the other remark is that the significance of a maritime discovery, however great at first, may become still greater with the lapse of time. Magellan, in his ever memorable voyage, not only penetrated to and crossed the Pacific, but discovered the Philippine Islands, and claimed them for the monarch who had sent him forth. His appropriation of them for the Crown of Spain, to which during these three centuries and a half they have brought no benefit, has been the cause which has led the republic of the United States to depart from its traditional policy of holding to its own continent by taking them as a prize--a distant and unexpected prize--of conquest. [Illustration: HOW NATURE DETERMINES THE SITES OF CITIES Most towns and communities founded more than 300 years ago were on easily defensible hills, by the side of navigable rivers, or inlets of the sea. Our illustrations show (1) Naples, (2) Bonsuna, (3) Old Port and hill of Marseilles, (4) Monaco, (5) St. Cézaire, and (6) the Greek Monastery of St. Balaam. Photos. by Frith and Underwood & Underwood ] [Illustration: THE SHIFTING OF THE CENTRE OF THE WORLD’S COMMERCE These two maps, which have been very carefully prepared from the most reliable authorities, indicate at a glance the relative importance of the Mediterranean and the Atlantic as highways of commerce in the time of Julius Cæsar, B.C. 102-44. ] [Illustration: HOW THE MEDITERRANEAN HAS GIVEN PLACE TO THE ATLANTIC Here is the contrast to the opposite page. In our time the Atlantic has become the centre of the world’s commerce, and the Mediterranean has sunk in importance. It would be almost deserted but for the routes to India via the Suez Canal. ]