Not only was foreign trade changed from the south and east of Europe to the west, from the city-states to nations, from land-routes to ocean- routes; but the vessels which sailed the Atlantic were larger, stronger, and more numerous, and they sailed with amazing confidence and safety, as compared with the fragile caravels and galleys of a few centuries before. The cargoes they carried had changed too. The comparative cheapness of water-transportation had made it possible profitably to carry grain and meat, as well as costly luxuries of small bulk such as spices and silks. Manufactures were an important item. Moreover, new commodities came into commerce, such as tea and coffee. The Americas sent to Europe the potato, "Indian" corn, tobacco, cocoa, cane-sugar (hitherto scarce), molasses, rice, rum, fish, whale-oil and whalebone, dye-woods and timber and furs; Europe sent back manufactures, luxuries, and slaves. [Sidenote: Slavery] Slaves had been articles of commerce since time immemorial; at the end of the fifteenth century there were said to have been 3000 in Venice; and the Portuguese had enslaved some Africans before 1500. But the need for cheap labor in the mines and on the sugar and tobacco plantations of the New World gave the slave-trade a new and tremendous impetus. The Spaniards began early to enslave the natives of America, although the practice was opposed by the noble endeavors of the Dominican friar and bishop, Bartolomé de las Casas. But the native population was not sufficient,--or, as in the English colonies, the Indians were exterminated rather than enslaved,--and in the sixteenth century it was deemed necessary to import negroes from Africa. The trade in African negroes was fathered by the English captain Hawkins, and fostered alike by English and Dutch. It proved highly lucrative, and it was long before the trade yielded to the better judgment of civilized nations, and still longer before the institution of slavery could be eradicated. [Sidenote: Effects on Industry and Agriculture] The expansion of trade was the strongest possible stimulus to agriculture and industry. New industries--such as the silk and cotton manufacture--grew up outside of the antiquated gild system. The old industries, especially the English woolen industry, grew to new importance and often came under the control of the newer and more powerful merchants who conducted a wholesale business in a single commodity, such as cloth. Capitalists had their agents buy wool, dole it out to spinners and weavers who were paid so much for a given amount of work, and then sell the finished product. This was called the "domestic system," because the work was done at home, or "capitalistic," because raw material and finished product were owned not by the man who worked them, but by a "capitalist" or rich merchant. How these changing conditions were dealt with by mercantilist statesmen, we shall see in later chapters.