The system of the tonalpohualli can be best understood by imagining two wheels that are connected to each other, imagine La Piedra de Sol (Sun Stone) in Mexico City.

According to Aztec cosmology, the universe exists in a delicate equilibrium that is in constant danger of being disrupted by shifting powers and the forces that influence our lives. It is always on the brink a spiritual war of gods competing for supreme power. The notion that everything ultimately consists of two opposing forces is essential to the Aztec worldview. To prevent this from happening, the gods have been given their own space, their own time, their own social groups, etcetera, to rule over. The tonalpohualli tells us how time is divided among the gods.

There is more than one version of Aztec calendar. This particular model In is called the tonalpohualli or, the day-count. It has been called a sacred calendar because its main purpose is as a divinatory tool that divides the days and rituals between the gods.