The secret messages hidden in the Aztec Calendar

With roots in earlier Mesoamerican civilizations, notably the Olmec and the Maya who had developed sophisticated timekeeping systems long before the rise of the Aztec Empire. 

A sophisticated calendar system spread across nearly every village in central Mexico, where a particular version became firmly established.

While every child understood the basic elements, only the priests who had studied the deeper aspects of the system ventured into more obscure branches of the knowledge.

What made it unique is that this calendar had two cycles running simultaneously.

The solar calendar included eighteen months, each containing twenty days, with an additional five unnamed days added at the end, making 365 days in total.

The ceremonial calendar, on the other hand, comprised thirteen months of twenty days each, totaling 260 days.

Both cycles worked in parallel, meaning that each day could be understood in two different contexts: one according to the solar cycle and another in relation to ceremonial time. 

After they settled in the Valley of Mexico in the 14th century, the Aztecs, or Mexica as they called themselves, likely adopted and refined these earlier Mesoamerican systems.

As relative latecomers to the region, they absorbed much of the cultural and scientific knowledge of the civilizations that had preceded them.

The most famous representation of the Aztec Calendar is the Sun Stone, a massive carved disk discovered in Mexico City's main square, the Zócalo, on December 17, 1790.

The true function of this monumental sculpture, often mistakenly referred to as the 'Aztec Calendar', remains debated among scholars.

Some argue it might have been a cosmic model linked to Aztec religious ceremonies.

However, it contains a detailed and complex representation of the Aztec cosmological and calendar systems, which makes it a key artifact in the study of the Aztec Calendar.

Although often called the Mesoamerican Calendar, the Aztec Calendar was actually a combination of two interlocking systems: the Tonalpohualli, or sacred 260-day calendar believed to have originated with the Olmec civilization, and the Xiuhpohualli, or solar calendar.

The Tonalpohualli consisted of 20 day signs and 13 numbers, which rotated to create a cycle of 260 unique days.

Each day had a specific name and symbol with its own divinatory and ritual significance.

Primarily used for religious purposes, it played a central role in Aztec rituals and ceremonies.

The Xiuhpohualli, or 365-day solar calendar, was similar to our modern calendar as it followed the solar year.

It was divided into 18 months of 20 days each, with an additional five 'unlucky' days at the end of the year known as Nemontemi.

The Nemontemi were considered a dangerous time when the boundaries between the living and the dead were particularly thin.

The Xiuhpohualli was used for practical purposes such as agriculture and taxation, and each of its 18 months was associated with a specific festival.

Interlocking, the Tonalpohualli and the Xiuhpohualli created a 52-year cycle known as the Calendar Round or Xiuhmolpilli.

Two cycles of time aligned at the end of fifty-two solar years, forming a complete unit of great importance.

This span, called a "bundle," held the same value to them as a century does today.

Each year had a unique name, tied to the ceremonial calendar's key number: thirteen.

They divided the fifty-two years into four groups of thirteen, creating an organized structure that allowed them to track time precisely and consistently.

The naming of each year followed a repetitive sequence involving four symbols: Reed, Flint-knife, House, and Rabbit.

For instance, the first year was One Reed, and the thirteenth was Thirteen Reed.

Once the initial cycle ended, the next began with One Flint-knife. This simple but effective system repeated across the fifty-two years, allowing them to easily mark the passage of time and recognize recurring patterns.

The completion of this cycle was considered a full cycle of life and was marked with a New Fire ceremony, a major event where all the fires in the Aztec realm were extinguished and relit.

Known for its rich symbols and iconography, the Aztec Calendar had elements that carried profound meaning within the Aztec cosmological view.

Its most famous representation was the Sun Stone, which had, at its center the face of the sun god Tonatiuh, which represented the current era, or the 'Fifth Sun'.

His tongue, shaped like a flint knife, jutted out and signified the sacrificial nature of this era.

However, some scholars suggested the central figure could be the earth deity Tlaltecuhtli or another solar god.

Four squares surrounded the central figure; each one represented one of the four previous eras or 'suns', associated with a different deity and form of destruction.

The next ring contained the 20 day signs of the Tonalpohualli, each with its own unique symbol.

These included animals like the jaguar and eagle, and natural elements like water and wind.

Each day sign was associated with a particular deity and had its own set of characteristics and meanings.

Beyond the day signs, two fire serpents encircled the stone; their tails were at the bottom, and their bodies rose up on either side to meet at the top.

These serpents (Xiuhcoatl) were associated with the sun god Huitzilopochtli and were seen as symbols of time and the solar cycle.

Between them, at the top of the stone, was a date, '13 Reed', which was believed to be the coronation date of the Aztec emperor Moctezuma II.

The outermost ring of the stone consisted of two Xiuhcoatl, or fire serpents, which represented the transformation of the earth.

The serpents' bodies were covered in star symbols and rose up on either side to meet at the top, where they were joined by a single head.

Because the intricate cycles of the Aztec Calendar required high mathematical precision and detailed knowledge of celestial movements, the Tonalpohualli, or 260-day calendar, was thought to have been based on the 584-day cycle of Venus, one of the most visible celestial bodies.

The number 260 also had many factors, which made it a versatile number for a calendar system that needed to align with other cycles.

The interplay of the 20 day signs and the 13 numbers in the Tonalpohualli created a cycle of 260 unique days, which demonstrated a sophisticated use of mathematical principles.

The Xiuhpohualli, or 365-day solar calendar, was based on the Aztecs' accurate observation of the solar year.

It was used for practical purposes such as agriculture. Its use demonstrated the Aztecs' understanding of the seasons and their ability to apply astronomical knowledge to everyday life.

The Aztec Calendar was a remarkable example of the integration of mathematics and astronomy in ancient cultures.

It demonstrated the Aztecs' ability to observe and understand the natural world and to apply this knowledge in a practical and meaningful way.

According to the Aztecs, the universe had gone through several cycles of creation and destruction, and each cycle represented a different age with its own sun and dominant life forms.

In their mythology, four previous worlds had existed, each ending in cataclysmic events that wiped out the life of that era.

They saw themselves as living under the fifth sun, which required human effort to sustain it.

In these earlier eras, the gods battled for supremacy, and this led to the collapse of the previous suns.

Each time, the world was recreated but with distinct changes that made it different from the one that came before.

The people of the fifth sun believed their gods had sacrificed themselves to create their current world, and they needed to repay this debt through rituals and sacrifices.

Much of their religious practices were shaped by this sense of duty, including human sacrifice, which they thought nourished the gods.

The Aztecs believed that the fate of the fifth sun rested in their hands, but they also feared its eventual destruction.

In their mythology, there was no guarantee that this current cycle would last forever.

As a result, they felt a sense of urgency in their worship, as they thought their actions directly impacted the survival of the universe.

As a result, the end of the Calendar Round was seen as a potential time for the next world-ending event.

To prevent this, the New Fire ceremony was held at the completion of each Calendar Round.

All fires in the Aztec realm were extinguished during this ceremony, which represented the end of the old world.

A new fire was then kindled in the chest of a sacrificed person, which represented the birth of the new world.

The new fire was used to relight all the fires in the community, which represented the renewal of life for another 52-year cycle.

In recent times, the concept of the end of the Aztec Calendar cycle has often been misunderstood or misrepresented, particularly in relation to the '2012 phenomenon', which incorrectly associated the end of a cycle in the Maya Calendar—a calendar system related to the Aztec Calendar—with the end of the world.

However, for the Aztecs, the end of the Calendar Round was not a prophecy of apocalypse but a time of renewal and rebirth, which demonstrated their belief in the cyclical nature of time and the cosmos.