But while gold is procured by the most simple process, to extract silver requires science, and an immense expenditure of labor and machinery, in delving to the very bowels of the earth, and in separating the slight percentage of pure silver from the mass of ore. In this exhausting labor, which is often assigned to convicts, Indians were employed until they gave up the ghost. The conquerors had appropriated to themselves the best-looking of the Indian females, while their husbands--for Indians marry very early in life--were consigned to the mines as laborers and carriers in the bowels of the mountain. From this promiscuous intercourse, so early introduced, has arisen the present mixed-blood population of Mexico. The offspring of sin, they are a nation of sinners. The pure Indians are the descendants chiefly of the unenslaved tribes, like the Tlascalans and Tezcucans, who carried on the subsequent wars of Cortez, and the whites are mostly descendants of later immigrations. In a former chapter we have seen that the evils which California suffered in the first years of its existence afflicted Mexico down to the time of the great inundation of 1629; and from the pen of an eye-witness we have given a picture of the state of society at that time. But during the five years that the water rested on the city, its superabundant wealth disappeared; many of the nobility and gentry withdrew to Puebla, carrying with them their treasures and their vices, while multitudes of the poorer classes perished. So that when the Virgin of Guadalupe, in her great mercy to an afflicted people, caused the earth to open and swallow up the great excess of waters, they had become a sobered and a more moral population. It is from this abating of the waters in the year 1634 that we have to date the origin of the present city of Mexico; for the foundations of all the buildings except those about the Cathedral were so much softened by five years of soaking that they could not be relied on; and a new city grew up upon new foundations. This is the Mexico of the present day; a city more elegant than substantial, and dependent more upon the plaster and colored washings of its walls than solid masonry for its apparent durability. THE VICEROY RAVILLAGIGEDO. It was the great Vice-king Ravillagigedo, toward the close of the last century (1789), who gave the finishing strokes to the city, and established its reputation as the finest city on this continent while the vice-kingdom continued. It was then one of the best-lighted cities to be found, while in its paving he expended the large sum of $347,715.[51] We have seen, in our own day and in our own large cities, the popular applause which follows the rigid enforcement of wholesome ordinances; and it may be well supposed that in a city like Mexico, such an unusual proceeding would elevate the fearless magistrate in popular estimation, and make him the subject of all kind of apocryphal anecdotes.