The men of Boston, and of New England in general, were, owing to natural circumstances, traders. They had found themselves in a land of splendid harbours, and so they went down to the sea in ships and trafficked upon its waters. It has of course been urged that this trade of the colonies was sadly restricted by the English people, who as a nation of shopkeepers were determined that "the cultivators of America might be confined to their shop."[207] For this reason the Navigation Act of 1660, on the lines of the famous Act of 1651, insisted on certain enumerated articles being landed in British ports only; and this was still further extended by two later enactments. But even Adam Smith allows that "though the policy of Great Britain with regard to the trade of her colonies has been dictated by the same mercantile spirit as that of other nations, it has, however, upon the whole, been less illiberal and oppressive than that of any of them."[208] The colonial system was in truth a mistake, but it never undermined the trade of the British settlements, as was the case in French Canada, owing to the corrupt and negligent methods of Bigot and his gang. The result was that the New England trader flourished. The trade had of course small beginnings; at first merely fish and fur were exported to Virginia. Then corn, cattle, and butter were sent to the West Indies, and exchanged for cotton and fruits. More distant voyages followed, and in 1643, wine, iron, and wool were imported from Spain. In the meantime iron had been discovered in Massachusetts by the younger Winthrop at Lynn and Braintree; and the Commissioners in 1665 certified that there was "good store of iron made in this province."[209] The Commissioners were, however, too optimistic, for the iron raised proved to be of inferior quality; partly because of this inferiority, but chiefly owing to trade regulations, scarcity of labour, and high wages, all cutlery and farm implements were imported from England well into the eighteenth century. The reported discovery of silver in Rhode Island in 1648 caused a nine days' wonder, and then the excitement subsided for nothing came of it. Lead was also found as early as 1650 in Lynn, but these mineral industries never rose to great importance under British rule.