Today the Aztecs seem a remote, alien people. Warlike and bloodthirsty, they are best known as the practitioners of human sacrifice. Yet their creative achievements are impressive: within the space of a hundred years they established the largest empire in Mesoamerican history, and at Tenochtitlan built a vast, shimmering city in a lake, a Venice of the New World whose temple-pyramids, elegant plazas and thronging markets defied the descriptive powers ( )