Human sacrifice and other forms of torture—self-inflicted or otherwise—were common to many parts of Mesoamerica. Thus the rite was nothing new to the Aztecs when they arrived to the Valley of Mexico, nor was it something unique to pre-Columbian Mexico. Other Mesoamerican cultures, such as the Purépechas and Toltecs, performed human sacrifices as well and from archaeological evidence, it probably existed since the time of the Olmecs (1200–400 BC), and perhaps even throughout the early farming cultures of the region. Although the extent of human sacrifice is unknown among several Mesoamerican civilizations, such as Teotihuacán, what distinguished Maya and Aztec human sacrifice was the importance with which it was embedded in everyday life.
In 1521, Spanish explorers such as Hernán Cortés conquered the Aztec capital of Tenochtitlan and made observations of and wrote reports about the practice of human sacrifice. Bernal Díaz del Castillo, who participated in the Cortés expedition, made frequent mention of human sacrifice in his memoir True History of the Conquest of New Spain. In addition, there are a number of second-hand accounts of human sacrifices written by Spanish friars, that relate to the testimonies of native eyewitnesses. The literary accounts have been supported by archeological research. Since the late 1970s, excavations of the offerings in the Great Pyramid of Tenochtitlan, and other archaeological sites, have provided physical evidence of human sacrifice among the Mesoamerican peoples.
A wide variety of interpretations of the Aztec practice of human sacrifice have been proposed by modern scholars. Many scholars now believe that Aztec human sacrifice was performed in honor of the gods. Most scholars of Pre-Columbian civilization see human sacrifice among the Aztecs as a part of the long cultural tradition of human sacrifice in Mesoamerica.
The Role of Sacrifice in Aztec Culture
Sacrifice was a common theme in the Aztec culture. In the Aztec "Legend of the Five Suns", all the gods sacrificed themselves so that mankind could live. Some years after the Spanish conquest of Mexico, a body of Franciscans confronted the remaining Aztec priesthood and demanded, under threat of death, that they desist from this traditional practice. The Aztec priests defended themselves as follows:
Life is because of the gods; with their sacrifice they gave us life.... They produce our sustenance... which nourishes life.
What the Aztec priests were referring to was a central Mesoamerican belief: that a great, continuing sacrifice of the gods sustains the Universe. A strong sense of indebtedness was connected with this worldview. Indeed, nextlahualli (debt-payment) was a commonly used metaphor for human sacrifice, and, as Bernardino de Sahagún reported, it was said that the victim was someone who "gave his service."
Human sacrifice was in this sense the highest level of an entire panoply of offerings through which the Aztecs sought to repay their debt to the gods. Both Sahagún and Toribio de Benavente (also called "Motolinía") observed that the Aztecs gladly parted with everything. Even the "stage" for human sacrifice, the massive temple-pyramids, was an offering mound: crammed with the land's finest art, treasure and victims, then buried underneath for the deities.
Additionally, the sacrifice of animals was a common practice, for which the Aztecs bred dogs, eagles, jaguars and deer. The cult of Quetzalcoatl required the sacrifice of butterflies and hummingbirds.
Self-sacrifice was also quite common; people would offer maguey thorns, tainted with their own blood and would offer blood from their tongues, ear lobes, or genitals. Blood held a central place in Mesoamerican cultures. The 16th-century Florentine Codex by Franciscan friar Bernardino de Sahagún reports that in one of the creation myths, Quetzalcóatl offered blood extracted from a wound in his own genitals to give life to humanity. There are several other myths in which Nahua gods offer their blood to help humanity.
Much like the role of sacrifice elsewhere in the world, it thus seems that these rites functioned as a type of atonement for Aztec believers. Aztec society viewed even the slightest tlatlacolli ('sin' or 'insult') as an extremely malevolent supernatural force. To avoid such calamities befalling their community, those who had erred punished themselves by extreme measures such as slitting their tongues for vices of speech or their ears for vices of listening. Other methods of atoning wrong doings included hanged themselves, or throwing themselves down precipices.
What has been gleaned from all of this is that the sacrificial role entailed a great deal of social expectation and a certain degree of acquiescence.
The Holistic Assessment of Human Sacrifice
According to Diego Durán's History of the Indies of New Spain, and a few other sources that are also based on the Crónica X, the Flower Wars were an act of ritual between the cities of Aztec Triple Alliance and Tlaxcala, Huexotzingo and Cholula. This form of ritual was motivated by the Mesoamerican cultures in 1450 after a serious of droughts and famine caused many deaths within the Mexican highlands. The droughts and damage to the crops were believed to be punishment by the gods for feeling disvalued instead of being honored properly. Therefore, the Flower Wars became a way to obtain human sacrifices in a very structured and ceremonial manner which were then used as offerings.
This type of warfare differed from regular political warfare, as the Flower war was also used for combat training and as first exposure to war for new military members. In addition, regular warfare included the use of long range weapons such as atlatl darts, stones, and sling shots to damage the enemy from afar. During Flower wars, warriors were expected to fight up close and exhibit their combat abilities while aiming to injure the enemy, rather than kill them. The main objective of Aztec Flower warfare was to capture victims alive for use later as human sacrifice, and offerings to the gods. When death occurred from battling in a Flower War, it was considered much more noble than dying in a regular military battle. Additionally, death in the Flower Wars contained religious importance as those who died were thought to live in heaven with the war god, Huitzilopochtli.
Human sacrifice rituals were performed during the appropriate times each month with the appropriate number of living bodies, and other goods, to properly appease and honor the gods. These individuals were previously chosen to be sacrificed, as was the case for people embodying the gods themselves, or were members of an enemy party which had been captured and prepared to be sacrificed. Even enemies of the Aztecs understood their roles as sacrifices to the gods since many also practiced the same type of religion. For many rites, the victim had such a quantity of prescribed duties that it is difficult to imagine how the accompanying festival would have progressed without some degree of compliance on the part of the victim. For instance, victims were expected to bless children, greet and cheer passers-by, hear people's petitions to the gods, visit people in their homes, give discourses and lead sacred songs, processions and dances.
A great deal of cosmological thought seems to have underlain each of the Aztec sacrificial rites. Most of the sacrificial rituals took more than two people to perform. In the usual procedure of the ritual, the sacrifice would be taken to the top of the temple. The sacrifice would then be laid on a stone slab, a chacmool, by four priests, and his/her abdomen would be sliced open by a fifth priest with a ceremonial knife made of flint. The most common form of human sacrifice was heart-extraction. The Aztec believed that the heart (tona) was both the seat of the individual and a fragment of the Sun's heat (istli). The chacmool was a very important religious tool used during sacrifices. The cut was made in the abdomen and went through the diaphragm. The priest would grab the heart which would be placed in a bowl held by a statue of the honored god, and the body would then be thrown down the temple's stairs. The body would land on a terrace at the base of the pyramid called an apetlatl.
Before and during the killing, priests and audience, gathered in the plaza below, stabbed, pierced and bled themselves as auto-sacrifice. Hymns, whistles, spectacular costumed dances and percussive music marked different phases of the rite.
The body parts would then be disposed of, the viscera fed the animals in the zoo, and the bleeding head was placed on display in the tzompantli or the skull rack. When the consumption of individuals was involved, the warrior who captured the enemy was given the meaty limbs while the most important flesh, the stomach and chest, were offerings to the gods.
Other types of human sacrifice, which paid tribute to various deities, killed the victims differently. The victim could be shot with arrows, die in gladiatorial style fighting, be sacrificed as a result of the Mesoamerican ballgame, burned flayed after being sacrificed, or drowned.
Those individuals who were unable to complete their ritual duties were disposed of in a much less honorary matter. This “insult to the gods” needed to be atoned therefore the sacrifice was slain while being chastised instead of revered. The conquistadors Cortés and Alvarado found that some of the sacrificial victims they freed “indignantly rejected [the] offer of release and demanded to be sacrificed.”
Scope of Human Sacrifice In Aztec Culture
Some post-conquest sources report that at the re-consecration of Great Pyramid of Tenochtitlan in 1487, the Aztecs sacrificed about 80,400 prisoners over the course of four days. This number is considered by Ross Hassig, author of Aztec Warfare, to be an exaggeration. Hassig states "between 10,000 and 80,400 persons" were sacrificed in the ceremony. The higher estimate would average 14 sacrifices per minute during the four-day consecration. Four tables were arranged at the top so that the victims could be jettisoned down the sides of the temple. Nonetheless, according to Codex Telleriano-Remensis, old Aztecs who talked with the missionaries told about a much lower figure for the reconsecration of the temple, approximately 4,000 victims in total.
Michael Harner, in his 1977 article The Enigma of Aztec Sacrifice, estimates the number of persons sacrificed in central Mexico in the 15th century as high as 250,000 per year. Fernando de Alva Cortés Ixtlilxochitl, a Mexica descendant and the author of Codex Ixtlilxochitl, estimated that one in five children of the Mexica subjects was killed annually. Victor Davis Hanson argues that a claim by Don Carlos Zumárraga of 20,000 per annum is "more plausible." Other scholars believe that, since the Aztecs often tried to intimidate their enemies, it is more likely that they could have inflated the number as a propaganda tool. The same can be said for Bernal Díaz's inflated calculations when, in a state of visual shock, he grossly miscalculated the number of skulls at one of the seven Tenochtitlan tzompantlis. The counter argument is that both the Aztecs and Diaz were very precise in the recording of the many other details of Aztec life, and inflation or propaganda would be unlikely. According to the Florentine Codex, fifty years before the conquest the Aztecs burnt the skulls of the former tzompantli. Mexican archeologist Eduardo Matos Moctezuma has unearthed and studied some tzompantlis.
Every Aztec warrior would have to provide at least one prisoner for sacrifice. All the male population was trained to be warriors, but only the few who succeeded in providing captives could become full-time members of the warrior elite. Accounts also state that several young warriors could unite to capture a single prisoner, which suggests that capturing prisoners for sacrifice was challenging. 
There is still much debate as to what social groups constituted the usual victims of these sacrifices. It is often assumed that all victims were 'disposable' commoners or foreigners. However, slaves - a major source of victims - were not a permanent class but rather persons from any level of Aztec society who had fallen into debt or committed some crime.  Likewise, most of the earliest accounts talk of prisoners of war of diverse social status, and concur that virtually all child sacrifices were locals of noble lineage, offered by their own parents. 
Likewise, it is doubtful if many victims came from far afield. In 1454, the Aztec government forbade the slaying of captives from distant lands at the capital's temples. Duran's informants told him that sacrifices were consequently 'nearly always... friends of the [Royal] House' - meaning warriors from allied states.
Sacrifices to Specific Gods
Huitzilopochtli was the tribal deity of the Mexica and, as such, he represented the character of the Mexican people and was often identified with the sun at the zenith, and with warfare, who burned down towns and carried a fire-breathing dragon or serpent. He was considered the primary god of the south and a manifestation of the sun, and a counterpart of the black Tezcatlipoca, the primary god of the north, "a domain associated with Mictlan, the underworld of the dead."
Huitzilopochtli was worshipped at the Templo Mayor, which was the primary religious structure of the Aztec capital of Tenochtitlan.The Templo Mayor consisted of twin pyramids, one for Huitzilopochtli and one for the rain god Tlaloc (discussed below). 
When the Aztecs sacrificed people to Huitzilopochtli (the god with warlike aspects) the victim would be placed on a sacrificial stone. The priest would then cut through the abdomen with an obsidian or flint blade. The heart would be torn out still beating and held towards the sky in honor to the Sun-God. The body would then be pushed down the pyramid where the Coyolxauhqui stone could be found. The Coyolxauhqui Stone recreates the story of Coyolxauhqui, Huitzilopochtli's sister who was dismembered at the base of a mountain, just as the sacrificial victims were.  The body would be carried away and either cremated or given to the warrior responsible for the capture of the victim. He would either cut the body in pieces and send them to important people as an offering, or use the pieces for ritual cannibalism. The warrior would thus ascend one step in the hierarchy of the Aztec social classes, a system that rewarded successful warriors.
During the festival of Panquetzaliztli, of which Huitzilopochtli was the patron, sacrificial victims were adorned in the manner of Huitzilopochtli's costume and blue body paint, before their hearts would be sacrificially removed. Representations of Huitzilopochtli called teixiptla were also worshipped, the most significant being the one at the Templo Mayor which was made of dough mixed with sacrificial blood. 
Tezcatlipoca was generally considered the most powerful god, the god of night, sorcery and destiny (the name tezcatlipoca means "smoking mirror", or "obsidian"), and the god of the north. The Aztecs believed that Tezcatlipoca created war to provide food and drink to the gods. Tezcatlipoca was known by several epithets including "the Enemy" and "the Enemy of Both Sides", which stress his affinity for discord. He was also deemed the enemy of Quetzalcoatl, but an ally of Huitzilopochtli. Tezcatlipoca had the power to forgive sins and to relieve disease, or to release a man from the fate assigned to him by his date of birth; however, nothing in Tezcatlipoca's nature compelled him to do so. He was capricious and often brought about reversals of fortune, such as bringing drought and famine. He turned himself into Mixcoatl, the god of the hunt, to make fire. To the Aztecs, he was an all-knowing, all-seeing nearly all-powerful god. One of his names can be translated as "He Whose Slaves We Are".
Some captives were sacrificed to Tezcatlipoca in ritual gladiatorial combat. The victim was tethered in place and given a mock weapon. He died fighting against up to four fully armed jaguar knights and eagle warriors.
During the 20-day month of Toxcatl, a young impersonator of Tezcatlipoca would be sacrificed. Throughout a year, this youth would be dressed as Tezcatlipoca and treated as a living incarnation of the god. The youth would represent Tezcatlipoca on earth; he would get four beautiful women as his companions until he was killed. In the meantime he walked through the streets of Tenochtitlan playing a flute. On the day of the sacrifice, a feast would be held in Tezcatlipoca's honor. The young man would climb the pyramid, break his flute and surrender his body to the priests. Sahagún compared it to the Christian Easter.
Both Xiuhtecuhtli and Huehueteotl were worshipped during the festival of Izcalli. For ten days preceding the festival various animals would be captured by the Aztecs, to be thrown in the hearth on the night of celebration.
To appease Huehueteotl, the fire god and a senior deity, the Aztecs had a ceremony where they prepared a large feast, at the end of which they would burn captives; before they died they would be taken from the fire and their hearts would be cut out. Motolinía and Sahagún reported that the Aztecs believed that if they did not placate Huehueteotl, a plague of fire would strike their city. The sacrifice was considered an offering to the deity.
Xiuhtecuhtli was also worshipped during the New Fire Ceremony, which occurred every 52 years, and prevented the ending of the world. During the festival priests would march to the top of the volcano Huixachtlan and when the constellation "the fire drill" (Orion's belt) rose over the mountain, a man would be sacrificed. The victims heart would be ripped from his body and a ceremonial hearth would be lit in the hole in his chest. This flame would then be used to light all of the ceremonial fires in various temples throughout the city of Tenochtitlan. 
Tlaloc is the god of rain, water, and earthly fertility. The Aztecs believed that if sacrifices were not supplied for Tlaloc, rain would not come, their crops would not flourish, and leprosy and rheumatism, diseases caused by Tlaloc, would infest the village.
Archaeologists have found the remains of at least 42 children sacrificed to Tlaloc at the Great Pyramid of Tenochtitlan. Many of the children suffered from serious injuries before their death, they would have to have been in significant pain as Tlaloc required the tears of the young as part of the sacrifice. The priests made the children cry during their way to immolation: a good omen that Tlaloc would wet the earth in the raining season. 
In the Florentine Codex, also known as General History of the Things of New Spain, Sahagún wrote:
"According to the accounts of some, they assembled the children whom they slew in the first month, buying them from their mothers. And they went on killing them in all the feasts which followed, until the rains really began. And thus they slew some on the first month, named Quauitleua; and some in the second, named Tlacaxipeualiztli; and some in the third, named Tocoztontli; and others in the fourth, named Ueitocoztli; so that until the rains began in abundance, in all the feasts they sacrificed children." 
Xipe Totec was worshipped extensively during the festival of Tlacaxipehualiztli, in which captured warriors and slaves were sacrificed in the ceremonial center of the city of Tenochtitlan. For forty days prior to their sacrifice one victim would be chosen from each ward of the city to act as ixiptla, dress and live as Xipe Totec. The victims were then taken to the Xipe Totec's temple where their hearts would be removed, their body dismembered and their body parts divided up to be later eaten. Prior to their death and dismemberment the victims skin would be removed, and worn by individuals who traveled throughout the city fighting battles and collecting gifts from the citizens. 
Calendar of Sacrifice
Main article: Aztec calendar
The 52-year cycle
The cycle of fifty-two years was central to Mesoamerican cultures. The Nahua's religious beliefs were based on a great fear that the universe would collapse after each cycle if the gods were not strong enough. Every fifty-two years a special New Fire ceremony was performed. All fires were extinguished and at midnight a human sacrifice was made. The Aztecs then waited for the dawn. If the Sun appeared it meant that the sacrifices for this cycle had been enough. A fire was ignited on the body of a victim, and this new fire was taken to every house, city and town. Rejoicing was general: a new cycle of fifty-two years was beginning, and the end of the world had been postponed, at least for another 52-year cycle.
Sacrifices were made on specific days. Sahagún, Juan Bautista de Pomar and Motolinía report that the Aztecs had eighteen festivities each year, one for each Aztec month.The table below shows the festivals of the 18-month year of the Aztec calendar and the deities with which the festivals were associated.  
|N°||Name of the Mexican month and its Gregorian equivalent||Deities and human sacrifices|
|I||Atlacacauallo (from February 2 to February 21)||Tláloc, Chalchitlicue, Ehécatl||Sacrifice of children and captives to the water deities|
|II||Tlacaxipehualiztli (from February 22 to March 13)||Xipe Tótec, Huitzilopochtli, Tequitzin-Mayáhuel||Sacrifice of captives; gladiatorial fighters; dances of the priest wearing the skin of the flayed victims|
|III||Tozoztontli (from March 14 to April 2)||Coatlicue, Tlaloc, Chalchitlicue, Tona||Type of sacrifice: extraction of the heart. Burying of the flayed human skins. Sacrifices of children|
|IV||Hueytozoztli (from April 3 to April 22)||Cintéotl, Chicomecacóatl, Tlaloc, Quetzalcoatl||Sacrifice of a maid; of boy and girl|
|V||Toxcatl (from April 23 to May 12)||Tezcatlipoca, Huitzilopochtli, Tlacahuepan, Cuexcotzin||Sacrifice of captives by extraction of the heart|
|VI||Etzalcualiztli (from May 13 to June 1)||Tláloc, Quetzalcoatl||Sacrifice by drowning and extraction of the heart|
|VII||Tecuilhuitontli (from June 2 to June 21)||Huixtocihuatl, Xochipilli||Sacrifice by extraction of the heart|
|VIII||Hueytecuihutli (from June 22 to July 11)||Xilonen, Quilaztli-Cihacóatl, Ehécatl, Chicomelcóatl||Sacrifice of a decapitated woman and extraction of her heart|
|IX||Tlaxochimaco (from July 12 to July 31)||Huitzilopochtli, Tezcatlipoca, Mictlantecuhtli||Sacrifice by starvation in a cave or temple|
|X||Xocotlhuetzin (from August 1 to August 20)||Xiuhtecuhtli, Ixcozauhqui, Otontecuhtli, Chiconquiáhitl, Cuahtlaxayauh, Coyolintáhuatl, Chalmecacíhuatl||Sacrifices to the fire gods by burning the victims|
|XI||Ochpaniztli (from August 21 to September 9)||Toci, Teteoinan, Chimelcóatl-Chalchiuhcíhuatl, Atlatonin, Atlauhaco, Chiconquiáuitl, Cintéotl||Sacrifice of a decapitated young woman to Toci, she was skinned and a young man wore her skin; sacrifice of captives by hurling from a height and extraction of the heart|
|XII||Teoleco (from September 10 to September 29)||Xochiquétzal||Sacrifices by fire; extraction of the heart|
|XIII||Tepeihuitl (from September 30 to October 19)||Tláloc-Napatecuhtli, Matlalcueye, Xochitécatl, Mayáhuel, Milnáhuatl, Napatecuhtli, Chicomecóatl, Xochiquétzal||Sacrifices of children, two noble women, extraction of the heart and flaying; ritual cannibalism|
|XIV||Quecholli (from October 20 to November 8)||Mixcóatl-Tlamatzincatl, Coatlicue, Izquitécatl, Yoztlamiyáhual, Huitznahuas||Sacrifice by bludgeoning, decapitation and extraction of the heart|
|XV||Panquetzaliztli (from November 9 to November 28)||Huitzilopochtli||Massive sacrifices of captives and slaves by extraction of the heart|
|XVI||Atemoztli (from November 29 to December 18)||Tlaloques||Sacrifices of children, and slaves by decapitation|
|XVII||Tititl (from December 19 to January 7)||Tona-Cozcamiauh, Ilamatecuhtli, Yacatecuhtli, Huitzilncuátec||Sacrifice of a woman by extraction of the heart and decapitated afterwards|
|XVIII||Izcalli (from January 8 to January 27)||Ixozauhqui-Xiuhtecuhtli, Cihuatontli, Nancotlaceuhqui||Sacrifices of victims representing Xiuhtecuhtli and their women (each four years), and captives. Hour: night, New Fire|
|Nemontemi (from January 28 to February 1)||Five ominous days at the end of the year, no ritual, general fasting|
Discussion of Primary Sources
Visual accounts of Aztec sacrificial practice are principally found in codices and some Aztec statuary. Many visual renderings in the codices were created for Spanish patrons, and thus may reflect European preoccupations and prejudices. Produced during the 16th century, the most prominent codices include the Ríos, Tudela, Telleriano-Remensis, Magliabechiano, and Sahagún’s Florentine. A contrast is offered in the few Aztec statues that depict sacrificial victims, which show an Aztec understanding of sacrifice. Rather than showing a preoccupation with debt repayment, they emphasize the mythological narratives that resulted in human sacrifices, and often underscore the political legitimacy of the Aztec state. For instance, the Coyolxauhqui stone found at the foot of the Templo Mayor commemorates the mythic slaying of Huitzilopochli's sister for the matricide of Coatlicue; it also, as Cecelia Kline has pointed out, "served to warn potential enemies of their certain fate should they try to obstruct the state's military ambitions."
In addition to the accounts provided by Sahagún and Durán, there are other important texts to be considered.
Juan de Grijalva, Hernán Cortés, Juan Díaz, Bernal Díaz, Andrés de Tapia, Francisco de Aguilar, Ruy González and the Anonymous Conqueror wrote about the Conquest of Mexico. Martyr d'Anghiera, Lopez de Gomara, Oviedo y Valdes and Illescas, while not in Mesoamerica, wrote their accounts based on interviews with the participants. Bartolomé de Las Casas and Sahagún arrived later to New Spain but had access to direct testimony, especially of the indigenous people.
Juan de Grijalva and Juan Díaz
Juan de Grijalva was one of the first Spaniards to explore Mexico and traveled on his expedition in 1518 with Juan Díaz. Diaz wrote Itinerario de Grijalva before 1520, in which he describes the aftermath of a sacrifice on an island off the coast of Veracruz. He said,
When he reached said tower the Captain asked him why such deeds were committed there and the Indian answered that it was done as a kind of sacrifice and gave to understand that the victims were beheaded on the wide stone; that the blood was poured into the vase and that the heart was taken out of the breast and burnt and offered to the said idol. The fleshy parts of the arms and legs were cut off and eaten. This was done to the enemies with whom they were at war.
Bernal Díaz corroborates Juan Díaz's history:
On these altars were idols with evil looking bodies, and that every night five Indians had been sacrificed before them; their chests had been cut open, and their arms and thighs had been cut off. The walls were covered with blood. We stood greatly amazed and gave the island the name isleta de Sacrificios [Islet of Sacrifices].
In The Conquest of New Spain Díaz recounted that, after landing on the coast, they came across a temple dedicated to Tezcatlipoca. "That day they had sacrificed two boys, cutting open their chests and offering their blood and hearts to that accursed idol". Díaz narrates several more sacrificial descriptions on the later Cortés expedition. Arriving at Cholula, they find "cages of stout wooden bars […] full of men and boys who were being fattened for the sacrifice at which their flesh would be eaten". When the conquistadors reached Tenochtitlan, Díaz described the sacrifices at the Great Pyramid:
They strike open the wretched Indian's chest with flint knives and hastily tear out the palpitating heart which, with the blood, they present to the idols […]. They cut off the arms, thighs and head, eating the arms and thighs at ceremonial banquets. The head they hang up on a beam, and the body is […] given to the beasts of prey.
According to Bernal Díaz, the chiefs of the surrounding towns, for example Cempoala, would complain on numerous occasions to Cortés about the perennial need to supply the Aztecs with victims for human sacrifice. It is clear from his description of their fear and resentment toward the Mexicas that, in their opinion, it was no honor to surrender their kinsmen to be sacrificed by them.
Hernán Cortés and the Anonymous Conqueror
Cortés was the Spanish conquistador whose expedition to Mexico in 1519 led to the fall of the Aztecs, and led to the conquering of vast sections of Mexico on behalf of the Crown of Castile.
Cortés wrote of Aztec sacrifice on numerous occasions, one of which in his Letters, he states:
They have a most horrid and abominable custom which truly ought to be punished and which until now we have seen in no other part, and this is that, whenever they wish to ask something of the idols, in order that their plea may find more acceptance, they take many girls and boys and even adults, and in the presence of these idols they open their chests while they are still alive and take out their hearts and entrails and burn them before the idols, offering the smoke as sacrifice. Some of us have seen this, and they say it is the most terrible and frightful thing they have ever witnessed.
The Anonymous Conqueror was an unknown travel companion of Cortés who wrote Narrative of Some Things of New Spain and of the Great City of Temestitan which details Aztec sacrifices. The Anonymous Conqueror wrote,
They lead him to the temple, where they dance and carry on joyously, and the man about to be sacrificed dances and carries on like the rest. At length the man who offers the sacrifice strips him naked, and leads him at once to the stairway of the tower where is the stone idol. Here they stretch him on his back, tying the hands to the sides and fastening the legs ... Soon comes the sacrificing priest--and this is no small office among them--armed with a stone knife, which cuts like steel, and is as big as one of our large knives. He plunges the knife into the breast, opens it, and tears out the heart hot and palpitating. And this as quickly as one might cross himself. At this point the chief priest of the temple takes it, and anoints the mouth of the principal idol with the blood; then filling his hand with it he flings it towards the sun, or towards some star, if it be night. Then he anoints the mouths of all the other idols of wood and stone, and sprinkles blood on the cornice of the chapel of the principal idol. Afterwards they burn the heart, preserving the ashes as a great relic, and likewise they burn the body of the sacrifice, but these ashes are kept apart from those of the heart in a different vase.
Proposed Explanations of Aztec Human Sacrifice
The Ecological Explanation
Different anthropological or other sources have attempted to explain a possible ecological explanation of the need for human sacrifices to supplement overall Aztec diet. Harner’s main argument lies within his claim that cannibalism is needed to assist the diet of the Aztecs. He claimed that very high population pressure and an emphasis on maize agriculture, without domesticated herbivores, led to a deficiency of essential amino acids amongst the Aztecs. As population increased and the amount of available game, mostly deer, decreased the Aztecs had to compete with other carnivorous mammals such as dogs, to find their food. In addition, the intensification of agriculture was believed to only help with gaining a surplus of carbs however not helpful with receiving proper nutrients.  Therefore, cannibalism of human sacrifices was needed to get the appropriate amount of protein per individual. Harris, author of Cannibals and Kings, has propagated the claim, originally proposed by Harner, that the flesh of the victims was a part of an aristocratic diet as a reward, since the Aztec diet was lacking in proteins.
However, Bernard Ortiz Montellano offers a counter argument and points out the faults of Harner’s sources. First off, Ortiz challenges Harner’s claim of the Aztecs needing to compete with other carnivorous mammals for protein packed food. Many other types of foods were available to the Aztecs, including meat from salamanders, fowls, armadillos, and weasels. These resources were also plenty available due to their need to subsist in Lake Texcoco, the place where the Aztecs had created their home. In addition, even if no herbivores were available to eat, the nutrients needed were found in the leaves and seeds of amaranth which also provided protein. Lastly, the Aztecs had a highly structured system in which chinampas and tribute provided a surplus of materials and therefore ensured the Aztec were able to meet their caloric needs.
Ortiz’s argument helps to frame and evaluate the gaps within Harner’s argument. Part of the issue with Harner’s reasoning for Aztec use of cannibalism was the lack of reliability of his sources. Harner recognized the numbers he used may be contradicting or conflicting with other sources, yet he continued to use these sources and claimed them as reliable. Ortiz qualifies Harner’s sources as Spanish propaganda, and states the need to critique primary sources of interactions with the Aztecs. By dehumanizing and villainizing Aztec culture, the Spaniards were able to justify their own actions for conquest. Therefore, encounters with sacrificial cannibalism were grossly exaggerated and Harner used the sources to aid his argument. Overall, ecological factors alone are not sufficient to account for human sacrifice and, more recently, it is posited that religious beliefs have a significant effect on motivation.
The Religious Explanation
Sacrifices were ritualistic and symbolic acts accompanying huge feasts and festivals, and were a way to properly honor the gods. Victims usually died in the "center stage" amid the splendor of dancing troupes, percussion orchestras, elaborate costumes and decorations, carpets of flowers, crowds of thousands of commoners, and all the assembled elite. Aztec texts frequently refer to human sacrifice as neteotoquiliztli, “the desire to be regarded as a god”. These members of the society became an ixiptla—that is, a god's representative, image or idol.
For each festival, at least one of the victims took on the paraphernalia, habits, and attributes of the god or goddess whom they were dying to honor or appease. Through this performance, it was said that the divinity had been given 'human form'—that the god now had an ixitli (face). Duran says such victims were 'worshipped... as the deity' or 'as though they had been gods'. Even whilst still alive, ixiptla victims were honored, hallowed and addressed very highly. Particularly the young man who was indoctrinated for a year to submit himself to Tezcatlipoca's temple was the Aztec equivalent of a celebrity, being greatly revered and adored.
Posthumously, their remains were treated as actual relics of the gods which explains why victims' skulls, bones and skin were often painted, bleached, stored and displayed, or else used as ritual masks and oracles. For example, Diego Duran's informants told him that whoever wore the skin of the victim who had portrayed god Xipe (Our Lord the Flayed One) felt he was wearing a holy relic. He considered himself 'divine'.
The Political Explanation
Politically human sacrifice was important in Aztec culture as a way to represent a social hierarchy between their own culture and the enemies surrounding their city. Additionally, it was a way to structure the society of the Aztec culture itself. The hierarchy of cities like Tenochtitlan were tiered with the Tlatoani (emperor) on the top, the remaining nobles (pipiltin) next who managed the land owned by the emperor. Then the warriors, the pochteca (merchants), commoners and farmers. Then the lowest level of the hierarchy consisted of slaves and indentured servants.  The only way of achieving social mobility was through successful performance as a warrior. This shows how important capturing enemies for sacrifice was as it was the singular way of achieving some type of “nobility.”
Within the system of organization based on hierarchy, there was also a social expectation contributing to the status of an individual at the time of their sacrifice. An individual was punished if unable to confidently address their own sacrifice, i.e. the person acted cowardly beforehand instead of brave.  Then, instead of being sacrificed honorably, their lowly death paralleled their new lowly status. Where one’s body traveled in the afterlife also depended on the type of death awarded to the individual. Those who died while being sacrificed or while battling in war went to the second-highest heaven, while those who died of illness were the lowest in the hierarchy. Those going through the lowest hierarchy of death were required to undergo numerous torturous trials and journeys, only to culminate in a somber underworld. Additionally, death during Flower Wars was considered much more noble than death during regular military endeavors.
- Diaz de Castillo, Bernal. The True History of the Conquest of New Spain. p. 206.
- Harner, Michael (1977). "The Ecological Basis for Aztec Sacrifice". American Ethnologist. 4 (1). doi:10.1525/ae.1977.4.1.02a00070.
- Isaac, Barry L (1983). "The Aztec "Flowery War": A Geopolitical Explanation". Journal of Anthropological Research.
- Hassig, Ross (2003). "El sacrificio y las guerras floridas". Arqueología mexicana. XI: 47.
- Aguilar-Moreno, Manuel (2006). Handbook to Life in the Aztec World. New York: Facts on File, Inc.
- Duran. The Aztecs: History of the Indies. pp. 141, 198.
- Duran, Book of the Gods and Rites, p. 167.
- Diaz, Bernal. The Conquest of New Spain. p. 159.
- Victor Davis Hanson (2000), Carnage and Culture, Doubleday, New York, pp. 194-195. Hanson, who accepts the 80,000+ estimate, also notes that it exceeded "the daily murder record at either Auschwitz or Dachau."
- Hanson, p. 195.
- Duverger (op. cit), 174-77
- Matos-Moctezuma, Eduardo (2005). Muerte a filo de obsidiana. Fondo de Cultura Económica. pp. 111–124.
- Cortes. Letter 105.
- Motolinia, History of the Indies, 118-119
- Ingham, John M. "Human Sacrifice at Tenochtitlan"
- Duran, Book of the Gods and Rites
- Bernardino de Sahagún, Historia General de las Cosas de la Nueva España (op. cit.), p. 76
- Sahagún, Ibid.
- David., Carrasco, (1982). Quetzalcoatl and the irony of empire : myths and prophecies in the Aztec tradition. Chicago: University of Chicago Press. ISBN 0226094871. OCLC 8626972.
- Duverger, Christian (2005). La flor letal: economía del sacrificio azteca. Fondo de Cultura Económica. pp. 83–93.
- Boone, Elizabeth. "Incarnations of the Aztec Supernatural: The Image of Huitzilopochtli in Mexico and Europe". Transactions of the American Philosophical Society. 79.
- Olivier (2003) pp. 14-15.
- Olivier (2003) pp. 14-15.
- Olivier (2003) pp. 14-15.
- Sahagún, Op. cit., p. 79
- López Austin 1998, p.10. Sahagún 1577, 1989, p.48 (Book I, Chapter XIII
- Bernardino de Sahagún, Historia General de las Cosas de la Nueva España (op. cit.), p. 83
- Roy 2005, p.316
- Sahagun, Fray Bernardino de (1569). Florentine Codex: General History of the Things of New Spain. p. 2.
- Miller, Mary (1993). The Gods and Symbols of Ancient Mexico and the Maya. Thames and Hudson Inc. p. 166-167, 142-143.
- Duverger, Christian (2005). La flor letal. Fondo de cultura económica. pp. 128–29.
- Sahagun Bk 2: 4
- Fernández 1992, 1996, pp.60-63. Matos Moctezuma 1988, p.181. Matos Moctezuma & Solis Olguín 2002, pp.54-5. Neumann 1976, pp.252.
- Carrasco, David (1995). "Give Me Some Skin: The Charisma of the Aztec Warrior". History of Religions. 35: 5.
- Bautista Pomar, Juan. Relación de Juan Bautista Pomar.
- Andros Foster, Elizabeth. Motolinia's History of the Indians of New Spain.
- Sahagun. Primeros Memoriales.
- Sahagún, Bernadino. Florentine Codex.
- Townsend, Richard (1979). State and Cosmos in the Art of Tenochtitlan. Washington, D.C.: Dumbarton Oaks, Trustees for Harvard University.
- Klein, Cecelia (1994). "Fighting with Femininity: Gender and War in Aztec Mexico" (PDF). Estudios de Cultura Nahuatl. 24: 219–253.
- Nuttall, Zelia (1910). "The Island of Sacrificios". American Anthropologist. 12: 258.
- Díaz, Bernal (2005) . Historia verdadera de la conquista de Nueva España (Introducción y notas de Joaquín Ramírez Cabañas). Editorial Porrúa. p. 24.
- Díaz (op. cit.), p. 150
-  Dinesh D'Souza's article
- The Conquest of New Spain, chap. XLVI
- Cortés, Hernán (2005) . Cartas de relación. México: Editorial Porrúa. p. 26. "Y tienen otra cosa horrible y abominable y digna de ser punida que hasta hoy no habíamos visto en ninguna parte, y es que todas las veces que alguna cosa quieren pedir a sus ídolos para que más acepten su petición, toman muchas niñas y niños y aun hombre y mujeres de mayor edad, y en presencia de aquellos ídolos los abren vivos por los pechos y les sacan el corazón y las entrañas, y queman las dichas entrañas y corazones delante de los ídolos, y ofreciéndolos en sacrificio aquel humo. Esto habemos visto algunos de nosotros, y los que lo han visto dicen que es la más cruda y espantosa cosa de ver que jamás han visto".
-  - Narrative of Some Things of New Spain and of the Great City of Temestitan, México, Chapter XV, written by a Companion of Hernán Cortés, The Anonymous Conqueror.
- Anonymous Conqueror. Narrative of Some Things of New Spain and of the Great City of Temestitan. XV.
- Website of the British Museum.
- 1927-2001., Harris, Marvin, (1978). Cannibals and kings : the origins of cultures. [London]: Fontana. ISBN 9780006356035. OCLC 16420059.
- De Montellano, Bernard R. Ortiz (1983-06-01). "Counting Skulls: Comment on the Aztec Cannibalism Theory of Harner-Harris". American Anthropologist. 85 (2): 403–406. ISSN 1548-1433. doi:10.1525/aa.1983.85.2.02a00130.
- Nahuatl dictionary.(1997). Wired humanities project. Retrieved September 2, 2012, from link.
- Peregrine, Peter N, and Melvin Ember. 2002
- Peregrine, Peter N, and Melvin Ember. 2002.
- Anonymous Conqueror (1917) [ca.1550]. Narrative of Some Things of New Spain and of the Great City of Temestitan, México (online reproduction by FAMSI, edited by Alec Christensen). Marshall H. Saville (trans. and ed.). New York: The Cortes Society. OCLC 6720413. Retrieved 2008-01-12.
- Carrasco, David (1999). City of Sacrifice: The Aztec Empire and the Role of Violence in Civilization. Boston, MA: Beacon Press. ISBN 0-8070-4642-6. OCLC 41368255.
- Díaz del Castillo, Bernal (1963) . The Conquest of New Spain. Penguin Classics. J. M. Cohen (trans.) (6th printing (1973) ed.). Harmondsworth, England: Penguin Books. ISBN 0-14-044123-9. OCLC 162351797.
- Durán, Diego (1994) [ca.1581]. The History of the Indies of New Spain. Civilization of the American Indian series, #210. Doris Heyden (trans., annot., and introd.) (English translation of Historia de las Indias de Nueva-España y Islas de Tierra Firme ed.). Norman: University of Oklahoma Press. ISBN 0-8061-2649-3. OCLC 29565779.
- Godwin, Robert W. (2004). One Cosmos under God: The Unification of Matter, Life, Mind & Spirit. Saint Paul, MN: Paragon House. ISBN 1-55778-836-7. OCLC 55131504.
- Hassig, Ross (1988). Aztec Warfare: Imperial Expansion and Political Control. Civilization of the American Indian series, no. 188. Norman: University of Oklahoma Press. ISBN 0-8061-2121-1. OCLC 17106411.
Ingham, John M. "Human Sacrifice at Tenochtitln." Society for Comparative Studies in Society and History 26 (1984): 379-400.
- León-Portilla, Miguel (1963). Aztec Thought and Culture: A Study of the Ancient Náhuatl Mind. Civilization of the American Indian series, #67. Jack Emory Davis (trans.). Norman: University of Oklahoma Press. OCLC 181727.
- Matos Moctezuma, Eduardo (1998). Vida y muerte en el Templo Mayor (in Spanish) (3rd ed.). México D.F.: Fondo de Cultura Económica. ISBN 968-16-5712-8. OCLC 40997904.
- Ortiz De Montellano, Bernard R. (June 1983). "Counting Skulls: Comment on the Aztec Cannibalism Theory of Harner-Harris". American Anthropologist. Arlington, VA: American Anthropological Association. 85 (2): 403–406. OCLC 1479294. doi:10.1525/aa.1983.85.2.02a00130.
- Ortiz De Montellano, Bernard R. (1990). Aztec Medicine, Health, and Nutrition. New Brunswick, NJ: Rutgers University Press. ISBN 0-8135-1562-9. OCLC 20798977.
- Sahagún, Bernardino de (1950–82) [ca. 1540–85]. Florentine Codex: General History of the Things of New Spain, 13 vols. in 12. vols. I-XII. Charles E. Dibble and Arthur J.O. Anderson (eds., trans., notes and illus.) (translation of Historia General de las Cosas de la Nueva España ed.). Santa Fe, NM and Salt Lake City: School of American Research and the University of Utah Press. ISBN 0-87480-082-X. OCLC 276351.
- Schele, Linda; Mary Ellen Miller (1992). Blood of Kings: Dynasty and Ritual in Maya Art. Justin Kerr (photographer) (2nd paperback edn., reprint with corrections ed.). New York: George Braziller. ISBN 0-8076-1278-2. OCLC 41441466.