Schouten's epoch-making discovery opened up the way for countless Dutch and English ships to ply a contraband trade with the towns of the Pacific coast, but did not induce the Spanish government to change its time-honoured policy or vary its trade routes. America was treated as the private property of the sovereign of Castile, and its commerce was to be exploited for his sole benefit. No Spaniard was allowed to freight a ship for the colonies, or to buy a pound of goods thence, without obtaining a special permission and paying for that privilege. Cadiz was the only port in Spain from which ships were permitted to sail for America, and the whole trade was farmed out to a ring of Cadiz merchants. To protect this monopoly and to prevent the export of gold and silver were the chief purposes of the Spanish colonial policy. Every port on the seaboard of Spanish South America was closed to trans-oceanic traffic, except Nombre de Dios on the north shore of the Isthmus. The towns on the Pacific and Caribbean coasts might admit coasting vessels properly identified as coming from the Isthmus and loaded with the consignments of the Cadiz monopolists, but the South Atlantic ports were absolutely closed so far as law could close them. Legally, no ships whatever, coasters or ocean carriers, could enter and unload at Buenos Aires. Her imports from Spain must first go to the Isthmus, be disembarked, and then transported across the mule-paths to the Pacific. Thence the goods had to go in coasters to Callao, in Peru, where they were again disembarked, transported up the Andean passes along the Bolivian plateau, and finally down into the Argentine plain. Under such conditions in the southern provinces European manufactures could only be sold at fabulous prices. On the other hand, such a system made exports impossible, except those of precious metals and valuable drugs. Hides, hair, wool, agricultural products, would not stand the cost of such long transport by land and sea. The Spanish authorities seem deliberately to have come to the conclusion that America should be confined to producing gold and silver, and they ruthlessly strangled all other industries. The Plate settlements especially suffered from the ruinous consequences of this system. Having no mines of precious metals, they were considered worthless; their interests were ignored, and their complaints given no attention. The mere existence of Buenos Aires was a source of anxiety to the monopolists and to the Spanish government. They feared that the English or Dutch might take possession of the mouth of the Plate and thence send expeditions to intercept gold and silver shipments along the overland routes. More immediate and real was the danger of the establishment of a contraband trade which would deprive the Cadiz merchants of their enormous profits on goods sent by the Isthmian route.