Scanty beyond all belief is our information about the people of the River Plate before the coming of the Spaniards. Mexico and Peru had goodly hoards of gold and silver, and were therefore objects of eager curiosity to the invaders whose chroniclers deigned to inquire into the traditions and mythology of their subjects; but the Silvery River--the Rio Plata--washed no treasure regions, and the settlements in that part of the continent were despised and neglected. Accordingly anthropologists have been obliged to work backwards; they can only infer the character of the prehistoric races by examining their descendants and such scanty traces as have survived from ancient days. And they are able to glean very little. The European belief[12] in a western land beyond the Pillars of Hercules was deep-rooted in classical antiquity. Beginning with a vague legend of a wonderful world in the west, it hardened into a semi-scientific hypothesis. The pseudo-Aristotle[13] seems to have been the first to treat this subject in a practical manner. He says: "Popular speech divides our inhabited world into islands and continents, but it ignores the fact that the whole is but a single island surrounded by the sea named the Atlantic. It is probable that there are other lands far away, some of which are larger, some smaller, than the world we know." He conjectured that on the other side of the Atlantic there was a great Terra Australis corresponding to Africa. Strabo opined that it would be possible to make a westward voyage to India were it not for the immense extent of the Atlantic, and if circumstances had been favourable there would probably have been an early discovery of America. It is believed that the Carthaginians visited Madeira and the Canaries. But the two maritime nations, Greece and Carthage, fell before Rome, and the triumphs of Rome were on land. Roman poets and panegyrists often indulged in vague and magnificent predictions of nations both in the remotest East and the remotest West who should come under the sway of Rome, and Seneca's[14] language is particularly precise, but they found the ocean an insuperable barrier. With the downfall of the Empire and the influx of barbarians progress was checked, but it is certain that about a thousand years after the birth of Christ some hardy Norsemen reached Greenland, and it is even conjectured that they penetrated into North America. Then, in the later Middle Ages, as the trading spirit grew stronger and the demand for slaves increased, the Portuguese began to make voyages down the African coast. But discovery became no longer a mere profitable adventure, it was imperatively demanded as the salvation of Christendom from ruin, when the Turks obtained possession of Constantinople and the caravan routes. Unless the rich Indian trade could be continued, two-thirds of the wealth of Europe would be destroyed, and thus the work of discovery was stimulated. The Portuguese