But the practice of buying and selling slaves in Europe can be traced as far back as the tenth century, when fairs were established in all the great cities. Prisoners of war, representing different nations at different times, according to the direction which the love of piracy and conquest took, were exposed at those great periodical sales of merchandise to the buyers who flocked from every land. The Northern cities around the Baltic have the distinction of displaying these human goods quite as early as Venice or any commercial centre of the South: the municipal privileges and freedom of those famous cities were thus nourished partly by a traffic in mankind, for whose sake privilege and right are alone worth having. Seven thousand Danish slaves were exposed at one fair held in the city of Mecklenburg at the end of the twelfth century. They had the liberty of being ransomed, but only distinguished captives could be saved in that way from being sold. The price ranged from one to three marks. It is difficult to tell from this how valuable a man was considered, for the relation of the mark to other merchandise, or, in other words, the value of the currency, cannot be represented by modern sums, which are only technically equivalent,--as a mark, for instance, was then held equal to eight ounces of silver.[7] That was not exorbitant, however, for those times, and shows that men were frequently exposed for sale. The merchants of Bristol used to sell a great many captives into Ireland; but it is recorded that the Irish were the first Christian people who agreed at length to put a stop to this traffic by refusing to have any more captives brought into their country. The Church had long before forbidden it; and there are no grounds for supposing that any other motive than humanity induced the Irish people to show this superiority to the conventions of the age.[8] From the essay by Schoelcher, entitled "The Slave-Trade and its Origin," which has been prepared with considerable research, we gather that the first negroes seen in Portugal were carried there in 1441. Antonio Gonzales was the name of the man who first excited his countrymen by offering for sale this human booty which he had seized. All classes of people felt a mania like that which turns the tides of emigration to Australia and California. Nothing was desired but the means of equipping vessels for the coast of Guinea. Previously to this a few Guanches from the Canaries had been exposed for sale in the markets of Lisbon and Seville, and there were many Moorish slaves in Spain, taken in the wars which preceded the expulsion of that nation. But now there was a rapid accumulation of this species of property, fed by the inexhaustible soil of Africa, whence so many millions of men have been reaped and ploughed into the soils of other lands.