One of the greatest difficulties encountered in any attempt to understand Aztec mythology is the multiplicity of gods and the diversity of attributes of the same god. This is due, as has been said, to the fact that Aztec religion was in a period of synthesis, in which there were being grouped together, within the concept of a single god, different capacities that were considered to be related. Quetzalcoatl, one of the greatest of the gods, provides an example of how different and seemingly unrelated aspects were being synthesized in a single god. He was Quetzalcoatl, the god of wind, of life, and of the morning; the planet Venus, god of twins and of monsters; and so on. According to these diverse attributes, he was known by various names: Ehecatl, Quetzalcoatl, Tlahuizcalpantecuhtli, Ce Acatl, Xolotl, etc.

The name Quetzalcoatl means literally "quetzal-serpent" or "the plumed serpent," but since to the Mexican the feathers of the quetzal bird were a symbol of something precious and coatl also means "twin brother," the name Quetzal-coatl may also be translated esoterically as "the precious twin," thereby indicating that the morning and the evening star are one and the same, that is, the planet Venus, represented in the morning by Quetzalcoatl and in the afternoon by his twin brother, Xolotl. Therefore, Tlahuizcalpantecuhtli appears with two faces, one of a living man, the other in the form of a skull.

This identification of the morning and evening stars has given rise to many myths among mankind and explains almost all the legends associated with Quetzalcoatl. In reality, Venus does appear for some time as an evening star, then it disappears, and when it reappears, is a morning star. The myth explains this astronomical phenomenon by relating that Quetzalcoatl and his twin brother, Xolotl, descended to the world of the dead and, wandering in hell, underwent various trials imposed by the infernal gods.

According to the myth, Quetzalcoatl decided to ask the god of the underworld for the bones of dead men with which to create a new man, and the twin brothers set out on their journey. When they arrived in the underworld, they made their plea before Mictlantecuhtli, begging him for the bones, but since Quetzalcoatl knew, as the chronicler says, that the god of the dead was "double-dealing and mistrustful," he began to run as soon as he got them. Mictlantecuhtli, angered by his escape, pursued him and ordered the quail to attack him. Quetzalcoatl slipped during his flight, was attacked by the birds, fell, broke the bones, and scarcely had time to pick up the fragments and escape with them from the underworld. The two brothers conferred, and, in spite of the fact that the affair did not turn out as well as they had hoped, Quetzalcoatl offered a sacrifice over the bones. Sprinkling them with his own blood, he created a new race of men. But as the bone fragments were of different sizes, so too are the men and women in the world; and the quail, as a result of their daring pursuit of the god, were to be sacrificed and their blood sprinkled on the sacrificial altars, for they were the collaborators of the god of the underworld and had attempted to prevent the hero from carrying out his mission.

Men are, then, the children of Quetzalcoatl, and the god always appears in this benevolent guise, as their father and creator. The myth of the twin brothers spread beyond the borders of Mexico and Central America and is frequently found among other American peoples. Likewise, the flight of Quetzalcoatl from Tula to the mythical Tlillan Tlapallan, "the land of the black and the red," and his promise to return from the East in the year of his name, Ce Acatl, is but a mythical explanation of the death of the planet, his descent into the West, where the black and the red, night and day, merge, and the prophecy that he will reappear in the East as the morning star, preceding the sun.Therefore, when the conquistadors landed at Veracruz, in the year 1519, called Ce Acatl ("One Reed") in the Aztec calendar, Monte-zuma was sure that here was Quetzalcoatl, returning to take possession of his Toltec kingdom, which he had abandoned when he fled to Tlillan Tlapallan.

As the god of life, Quetzalcoatl appears as the constant benefactor of mankind, and so we find that after having created man with his own blood, he sought a way to nourish him. He discovered corn, hidden by the ants within a hill, and changing himself into an ant, stole a grain, which he later gave to man. He taught man how to polish jade and other precious stones and how to locate deposits of them. He showed him how to weave multicolored fabrics from the miraculous cotton that grew in different colors; he taught him how to do mosaic work with the feathers of the quetzal bird, the bluebird, the hummingbird, the macaw, and other birds with brilliant plumage. But above all he taught man science, thereby endowing him with the means to measure time and study the movements of the stars; he taught him how to arrange the calendar and devised ceremonies and fixed certain days for prayers and sacrifices.

Quetzalcoatl is a very ancient god. Among the Mayas and the Quiches he was known as Kukulkan and Gucumatz; and even though we do not know his name, he appears as the feathered serpent in the most ancient of the Teotihuacan ruins, predating the Toltec era. A Zapotec god is frequently pictured on the clay pots peculiar to this culture and its predecessors in the Valley of Oaxaca. This god has so many characteristics similar to those of Quetzalcoatl that he appears to be a representation of him. The multiplicity of Quetzalcoatl's functions also indicates the great antiquity of his cult and the veneration in which he was held in all Mesoamerica. Perhaps the most important aspect of this god, still little known, is his relation to the concepts of holiness and sin. In the Toltec era, his struggle with his brother, Tezcatlipoca, assumes characteristics that are not only mythical but also historical.

In short, Quetzalcoatl is the very essence of saintliness; his life of fasting and penitence, his priestly character, and his benevolence toward his children, mankind, are evident in the material that has been preserved for us in the chronicles and in the picture-writing of the indigenous manuscripts. But side by side with this aspect of saintliness we find also in Quetzalcoatl an aspect of sin; and sin, to the indigenes, meant drunkenness and failure to observe sexual abstinence.

The sinner is pictured in the codices as the "eater of filth." Sin was just that, a moral filth, and it assumed tragic proportions when Quetzalcoatl, the very archtype of saintliness, allowed himself to be dragged into drunkenness and incontinence. To be sure, he was led astray by Tezcatlipoca, the god of evil, and, as has been said, in the long-drawn-out struggle that these two rival gods carried on, creating and destroying the universe only to create and destroy it again, Tezcatlipoca, the evil one, finally used seduction as a means of making the holy Quetzalcoatl fall into sin. In like manner, according to another myth, the goddess of love and beauty, Xochiquetzal, seduced the virtuous Yappan, provoking the wrath of the gods, who changed him into a scorpion.

In this way the cosmic struggle was changed into a moral struggle, and later, when the Toltec king, the historical Quetzalcoatl, was forced to leave Tula, the priests and the faithful followers of Tezcatlipoca pursued him and forced him to abandon the central region of Mexico and flee to the lands of Veracruz, Tabasco, and Yucatan.

The hypothesis that Quetzalcoatl may have been an importation of European ideas to American soil should be completely discarded. Long before the American continent was discovered—that is, long before the European could have undertaken expeditions to the American continent, even before the Christian era—Quetzalcoatl was already in existence. The association of the white, long-bearded god of the legend with an Irish bishop or with the apostle St. Thomas is only one of many such errors that by dint of repetition acquire the dignity of truth. Quetzalcoatl, the bearded god, is a very ancient god of Mesoamerica. Even before the Christian era his cult was in existence in this region of the world. He is by no means a god foreign to Mexico; he is, on the contrary, one of the most important and characteristic gods of that part of the world.