over by the long succession of gentle Indians, who for centuries have heaped their boats with flowers, and floated over the dark water chanting low songs.
Humboldt went to inspect the pyramids of the sun and moon at Teotihuacan, and afterwards gave a prolonged study to mines, visiting first Moran and Real del Monte, northeast of the capital, and afterwards Guanajuato. Long before the arrival of the Spaniards, the natives of Mexico were acquainted with the working of subterranean veins to find metal. Cortés says that gold, silver, copper, lead, and tin were all sold in the markets of Tenochtitlan. They either collected grains of native gold in small baskets of slender rushes, or melted the metal into bars, like those now used in trade, represented in Mexican paintings. Humboldt found the methods of mining not advanced from the sixteenth century, without any of the improvements known in his time. The hard work was performed by Indians, the beasts of burden of the mines. They carried out the metal in bags on their backs, going up and down thousands of steps, in long files of fifty or sixty, men of seventy years old, and children of ten or twelve.
The mine of Valenciana, in Humboldt's time the most celebrated of Guanajuato, and the richest then known in Mexico, was not much wrought until the end of the eighteenth century, although it had been somewhat worked by the early Indians and the first Spanish settlers. In 1760, a poor man named Obregon, a Spaniard, began to explore a new vein. As he was a worthy man, he found friends willing to advance small sums from time to time to carry on his
