I have seen many prickly pears in different places, but never such specimens as those that were growing among the stones in this old quarry. They had gnarled and knotted trunks of hard wood, and were as big as pollard-oaks; their age must have been immense; but, unfortunately, one could not measure it, or it would have been a good criterion of the age of the quarry, which had not only been excavated but abandoned before their time. In one of the caves was a human skeleton, blanched white and clean, and near it some one has stuck a cross, made of two bits of stick, in the crevices of a heap of stones. Returning to the entrance of the quarry, well loaded with stone hammers and knives, we sat down to breakfast, in a cave, where our man had established himself with the horses. An attempt on my part to cut German sausage with an obsidian knife proved a decided failure. We had already been struck by the appearance of the two pyramids of Teotihuacán, when we passed by Otumba on our way to Mexico. The hills which skirt the plain are so near them as to diminish their apparent size; but even at a distance they are conspicuous objects. Now, when we came close to them, and began by climbing to their summits, and walking round their terraces, to measure ourselves against them, we began gradually to realize their vast bulk; and this feeling continually grew upon us. Modern architecture strives to unite the greatest possible effect with the least cost; and the modern churches of southern Europe and Spanish America, with their fine tall facades fronting the street, and insignificant little buildings behind, show this idea in its fullest development. Pyramids are built with no such object, and make but little show in proportion to their vast mass of material; but then one gets from them a sense of solid magnitude that no other building gives, however vast its proportions may be. Neither of us had ever seen the Egyptian pyramids. Even in Mexico these of Teotihuacán are not the largest; for, though the pyramid of Cholula is no higher, it covers far more ground. Were these monuments in Egypt, they would only rank, from their size, in the second class. As has often been remarked, such buildings as these can only be raised under peculiar social conditions. The ruler must be a despotic sovereign, and the mass of the people slaves, whose subsistence and whose lives are sacrificed without scruple to execute the fancies of the monarch, who is not so much the governor as the unrestricted owner of the country and the people. The population must be very dense, or it would not bear the loss of so large a proportion of the working class; and vegetable food must be exceedingly abundant in the country, to feed them while engaged in this unprofitable labour.