It has to be remembered that the temporal power of the Arabs—of the Moslems generally—depended not on the use of great military power, but on controlling a vast trade area. This control was possible because the land was continuous and the sea for all practical purposes was not; it was effective because the Arabs occupied that land which must always have extra ordinary significance, lying as it does between the Mediterranean on the one hand and the Persian Gulf and the Red Sea on the other. The Arabs had in fact the whole carrying trade that had belonged to Romans, Assyrians, Persians, the people of Central Asia as well as those of North-East Africa. This trade cannot have been great in amount compared with trade of the present time, because transport then was so much more difficult than now, but they had in their hands the trade of the world such as it was. The idea of trade had also been steadily extending. Men were beginning to depend on the results of trade. It was being found more and more profitable to exchange commodities produced in one area for those produced in another; that is, it was found that on the whole there was a saving of energy in using up some energy in carrying the productions of one land to another, rather than in producing all that was required in one place, even if that were possible. In particular, men were becoming accustomed to the idea that there was a way to the Indies almost entirely by water.
Further, the Roman Empire had been civilized. The chief men and their immediate dependents had grown accustomed to luxury, to the control for their own use of a superabundance of energy, to the accumulation of more energy than they could assimilate. Though Rome fell politically there still remained cities in Italy where such men lived accustomed to luxury, ti. e. to a variety of foods, clothing and house furnishings which could not be supplied in Italy itself. All these were brought from the ends of the earth by Arab trade.
Also Europe generally had been advancing in civiliza tion. States had been gradually appearing out of the ruins of the Roman Empire, buffeted into shape directly or indirectly by the menaces of the nomads from the east, the Arabs on the south, and the hardy seamen of the northern peninsulas. The standard of living of these new states had been gradually rising. The salt meat consumed in winter, when the production of the land ceased, was found to be more palatable if seasoned with spices, especially pepper ; the energy of food was more easily made available by increasing the appetite and digestive powers. Hence the trade in spices came to be of importance. This trade also was in the hands of the Arabs. Thus all the commodities carried were valuable in proportion to their bulk; they could " stand " transport not only by water but by land, and by land on camel or on horse, and the profits of the valuable trade were largely made by the Arabs.
But the Arabs had not conquered Europe, and there grew up in Europe in favourable spots trading towns which had enormous power. These favourable spots were naturally in Northern Italy, where luxuries were consumed and where there was easiest access to the northern lands of Europe. Venice in its sandy lagoons
enjoyed protection from land and sea and had an enor mous trade for many years, but Genoa and Pisa were also important trading-town republics. The great popu lations in Northern Italy " required bulky goods from close at hand, and so, because the ships were carrying goods, in any case, to them, through Genoa and Venice came a greater proportion of the valuable goods of the East than was brought to other parts." Thus these towns grew into still more important ports because such a trade, though small in amount, puts great profits into the hands of those who carry it on with success.
But as only valuable commodities could be brought from the Indies, men naturally thought that the Indies were rich lands, and as time went on there sprang up a desire on the part of Western nations to reach these new lands for themselves in order to bring home "riches" that had not first had to pay toll to the Arabs.
It is to be noticed now what lands border on the ocean. To give them their modern political names these are Portugal, Spain, France, the Netherlands, Germany, Denmark, Norway and Britain. These had all directly or indirectly received the impetus towards civilization from the centres on the Mediterranean, but till the discovery of the ocean they were on the outer fringe of the world. Though the Roman Empire fell, the centre of interest was still in the Mediterranean, routes converged on the Mediterranean and on the east end of it, and trade had there its greatest volume.
At first sight it would seem that any one of these lands might have discovered the ocean. In a sense the Norwegians had discovered it. The poverty of their soil almost compels men to eke out existence by fishing. The Inner Lead, protected by the rampart of islands, forms a " Great North Road " of which the innumerable fiords are byways. There is a nursery of hardy seamen here, and it is no wonder that men had gone out west wards across the ocean as well as southwards along the coasts, where they had settled as crofters and fishers wherever they could find a foothold. The Danes and Saxons were less naturally sailors, and crossed the North Sea rather because of force from behind—the pressure of the nomads from the East—than because of any natural liking for the sea. A sea-empire was for a moment, under Sweyn and Cnut, based on the North Sea, but this led to no discovery of the oneness of the ocean. It was but an empire of the same kind as the early Roman based on the Mediterranean Sea; in this northern empire there were fewer people and less natur ally available energy, and it lasted only a short time. Even the Norsemen's discovery of America had no effect on the course of history. It was merely another land farther removed from the world, cold and provid ing little energy. Neither then nor later was there any very great interest in the question whether there was one ocean or two, for it did not affect the daily life of the people.