One of the fundamental principles of the Mesoamerican cosmovision lay in the alternation of rainy and dry seasons, an essential cycle for the cultivation of maize. For the ancient Nahuas, Tlaloc, “he who lies upon the earth,” or the god of the celestial waters, governed the hydrological forces indispensable to agriculture: rain, clouds, lightning, and thunder. Colonial sources describe Tlalocan as his mythical dwelling, a paradise where the forces of fertility, sustenance, and subterranean wealth are safeguarded. This place is associated with the underworld, the sea, and hills; it is the destination of those who die by drowning or from illnesses of an aquatic nature, such as gout or lightning strikes. The god of water shares his functions with the Tlaloques, his attendants or lesser water deities, and with Chalchiuhtlicue, his consort and goddess of terrestrial waters.
The figure of Tlaloc is characterized by his serpentine and jaguar-like features, goggle eyes, and fangs. He is typically adorned with paper or feather headdresses and carries a blue serpent staff as a symbol of lightning. His face is painted black and, in some cases, the lips are painted blue. In the Templo Mayor of Tenochtitlan, Tlaloc shares the principal temple structure with Huitzilopochtli, the solar and war deity, as an expression of the cosmic balance required between water and fire.
His connection with death and the regeneration of the earth, the verdure of plants, and the abundance of food is manifested in various myths, as well as in his title Tlamacazqui, “the Giver.” As a creator god, Tlaloc also participates in the origin of the Moon at Teotihuacán, a celestial body closely associated with fertility, pulque, and water. Indeed, “the pulque of the earth” is another of its designations.
Tlaloc is considered to be the patron of the eighth heaven because of his dominion over the celestial waters. In the “Count of Days/Destinies” (tonalpohualli), he corresponds to the sign Ce Quiáhuitl (1 Rain), considered a day of ill fortune. In the Tonalámatl, he appears as the eighth of the thirteen Lords of the Days and as one of the nine Lords of the Night. His figure expresses the close relationship between the sacred and productive cycles. His power to grant or withhold rain made him a fundamental deity for the agricultural economies of Mesoamerica, which is why offerings, rituals, and rubber-stained paper offerings were dedicated to him during various twenty-day ceremonial periods.
Friar Bernardino de Sahagún describes the feast of Atlcahualo (February, during the dry season) as one of the principal celebrations in honor of Tlaloc and the mountains, a time when petitions for rain began.
To this day, devotion to the Pre-Hispanic water deities remains alive throughout the agricultural cycle, having been symbolically reworked through the figures of Catholic saints such as Saint Michael the Archangel and Saint John. Likewise, sacred geography continues to play a central role: mountains, caves, and bodies of water remain the principal ritual sites, conceived as thresholds to the underworld and as places of exchange with the owners of the waters.