Dutch, seeking a passage northeast or northwest through Arctic seas, that would enable them to evade the monopoly granted by the Pope. =152. Effect of the discoveries on the field of commerce; growth of a world commerce.=—Contrasting medieval and modern commerce we find that the discoveries produced great changes both in the area and in the articles of trade. Maritime commerce in the Middle Ages was restricted in general to the seas of Europe (Baltic, North, Mediterranean, Black) and to the edge of the Atlantic; exchange was hindered not only by physical obstacles but also by the claims of various states to the exclusive control of inland waters (Hansa in the Baltic, Venice in the Adriatic). When once sailors had learned to leave the coast and steer boldly into the open ocean, secure in the consciousness that they were approaching not a “sea of darkness” but a land much like that which they had left behind them, the ocean became a means of uniting continents rather than of separating them. The principle that the sea is free to all was not accepted, it is true, for some time; states tried to extend to the open sea the same narrow principle of exclusion that had been practised with respect to interior waters. These claims led to bitter national conflicts in the sixteenth and seventeenth centuries, but they fell gradually into oblivion as the hopelessness of making them effective became apparent; and the European commerce of a former period expanded into a world commerce. =153. Effect of the discoveries on the wares of commerce.=—Europe had become acquainted with Asiatic wares in the course of the Levant trade, so that the market for them was well established when the first Portuguese ships returned from India. Transportation by the sea route, however, with its diminished costs and with the greatly increased cargoes, caused such a decline in the price of eastern goods that the market for them expanded immensely. What had before been costly luxuries for the rich became now a part of their regular necessaries, and became for other classes luxuries or comforts which they could afford to purchase. It is in this period that tea, coffee, and sugar became common articles of consumption in some of the European countries. The part played by those three articles in the commerce of an advanced country can be seen from the fact that before the end of the eighteenth century they formed _over one fourth_ of the total imports of England. Other wares, such as Indian textiles, which had been known to Europe before, but which were too bulky to pay for the import of cheaper grades, could now be placed on the market in large quantities, when protective duties did not exclude them.