Even after the Aztecs became masters of the surrounding country, they built towns round the lake, partly on the shore, and partly on piles in the water. The Spanish chroniclers mention Iztapalapán, and many other towns, as built in this way. Like the Swiss tribes, the early inhabitants of Mexico depended much upon their fishing, for which their position gave them great facilities.
If you look at the arms of the Mexican Republic, on a passport or a silver dollar, you will see a representation of a rock surrounded by water. On the rock grows a cactus, and on the cactus sits an eagle with a serpent in his beak. The story is that the wandering tribe preserved a tradition of an oracle which said that when they should find an eagle, holding a serpent, and perched on a cactus growing out of a rock, then they should cease their wanderings. On an island in the lake of Tezcuco, they found eagle, serpent, cactus, and rock, as described, and they settled there in due course. What fragment of truth is hidden in this myth it is hard to say. Tenochtitlán means “The Stone-cactus place;” and the Aztec picture-writings express its name by a hieroglyph of a prickly pear growing on a rock. Putting this history out of the question, the Aztecs had excellent reasons for choosing this peculiar site for their city; but these reasons were not equally valid in the case of the new invaders. For them the surrounding salt-water was not needed as a protection, and was merely a nuisance. Every year, when the lake rose, the place was flooded, with enormous damage to the property of the inhabitants; and sometimes an inundation of greater depth than usual threatened as complete a destruction as Cortes and the Tlascalans had made. At the best of times, the site was a salt-swamp, an ugly place to build upon. And, lastly, all the fresh water must be brought from the hills by aqueducts, which an enemy would cut