At the time of the Spanish conquest, the religion of the Aztecs was polytheistic, based on the worship of a multitude of personal gods, most of them with well-defined attributes. Nevertheless, magic and the idea of certain impersonal and occult forces played an important role among the people. There was, in addition, among the uneducated classes tendency to exaggerate polytheism by conceiving of as gods, also, what to the priests, were only manifestations or attributes of one god ( Caso, 1987 ).
Even though there was a magical and impersonal background in the religion of the Aztec people, as well as an exaggerated polytheism, there is also evidence to support that Aztec priests tried to reduce the multiple divinities to different aspects of the same god. When they adopted the gods of conquered peoples or received gods from peoples of more advanced cultures, the priests would always try to incorporate them, like the Romans, into their own national pantheon, by considering them as diverse manifestations of the gods they had inherited from the great civilizations which preceded them and from which they had derived their culture ( Leon-Portilla, 1970 ).
Although the Aztec priests tried to unite in a single concept the different gods of the different tribes the people as a whole would not admit that their local god was subject to any other or that he was only an attribute of a superior being. An exception to this generalized thought was Huitzilopochtli, the Aztecs' own tribal god, and other deities associated with him in the national myths kept alive by Aztec pride. In later legends this god is associated with the creation of the world, occupying a space similar to that held by the traditional Toltec and Teotihuacan gods and by those gods worshiped by the people of the Valley of Mexico before the volcano Xitle covered their homes with lava, several centuries before Christ ( Caso, 1987 ).
However, a very ancient school of philosophy held that the origin of all things was a single dual principle, masculine and feminine, that had created the gods, the world, and man. Nezahualcoyotl, the king of Texcoco, already preferred to worship an invisible god that could no longer be represented. He was called Tloque Nahuaque, or Ipalnemohuani, "the god of the immediate vicinity, that one through whom all live," who was placed above the heavens and in the highest realm and on whom all things depended. Even though this appears to be a monotheistic attitude it still acknowledged the existence and the worship of the other gods, it does indicate however, that in exceptional mentalities the philosophical desire for unity had already appeared and that men were seeking a single cause to explain all other causes, and a single god superior to all other gods ( Caso, 1987 ).
Therefore, when Nezahualcoyotl built a temple upon a pyramid of nine terraces representing the nine heavens, he did not place in the sanctuary that crowned the pyramid any image representing the god, since he could not be portrayed and must be conceived as pure idea. This single god of Nezahualcoyotl did not have much following, nor did he affect the religious life of the people. The gods of philosophers have never been popular, for they arise from the need of a logical explanation of the universe, while the common people require less abstract gods who will satisfy their sentimental need for love and protection ( Leon-Portilla, 1970 ).