A Spanish soldier describes Tenochtitlan: "The great city...has many broad streets, though among these are two or three pre-eminent. All travel by...canoes, as I have said, and without these they could neither leave their houses nor return to them." —Anonymous Spanish soldier Aztec Civilization by Lois Warburton, Lucent Books, 1995, page 60. Which of the following does this excerpt imply?