But these cases are exceptional. Bengal and Lombardy and Egypt have supported large populations under all kinds of government. The products of each country tend, moreover, to establish definite relations between it and other countries, and do this all the more as population, commerce, and the arts advance. When England was a great wool-growing and wool-exporting country, her wool export brought her into close political connection with the wool-manufacturing Flemish towns. She is now a cotton-manufacturing country, needing cotton which she cannot grow at all, and consuming wheat which she does not grow in sufficient quantities. Hence she is in close commercial relations with the United States on one side, which give her most of her cotton and much of her wheat, and with India, from which she gets both these articles, and to which she exports a large part of her manufactured cotton goods. [Sidenote: Common Needs make for Peace] So Rome, because she needed the corn of Egypt, kept Egypt under a specially careful administration. The rest of her corn came from Sicily and North Africa, and the Vandal conquest of North Africa dealt a frightful blow to the declining Empire. In these cases the common interest of sellers and buyers makes for peace, but in other cases the competition of countries desiring to keep commerce to themselves occasions war. The Spanish and Dutch fought over the trade to India in the earlier part of the seventeenth century, when the Portuguese Indies belonged to Spain, as the English and French fought in the eighteenth. And a nation, especially an insular nation, whose arable soil is not large enough or fertile enough to provide all the food it needs, has a powerful inducement either to seek peace or else to be prepared for maritime war. If such a country does not grow enough corn or meat at home, she must have a navy strong enough to make sure that she will always be able to get these necessaries from abroad. Attica did not produce all the grain needed to feed the Athenians, so they depended on the corn ships which came down from the Euxine, and were practically at the mercy of an enemy who could stop those ships. Of another natural source of wealth, the fisheries on the coast of a country, no more need be said than that they have been a frequent source of quarrels and even of war. The recognition of the right of each state to the exclusive control and enjoyment of the sea for three miles off its shores has reduced, but not entirely removed, the causes of friction between the fishermen of different countries. [Sidenote: Minerals and Civilisation]