Today I’m going to give a quick overview of the types of autosacrifice performed by the Aztecs during the days of the Empire in order shed some additional light on this very important religious practice.
Traditionally, the Aztecs would collect blood from their ears, lower legs (calf, shin, or just above the ankle), lip, tongue, or penis. The tools and methods used would vary depending on the worshipper’s preferences, the ritual context, and in at least some cases, the instruction of a priest. The Florentine Codex records the rite of confession to Tlazolteotl, and according to Sahagun, the confessor priest would prescribe required penances to atone for the disclosed sins — these penances often included various forms of bloodletting.
The most common methods of getting the blood were by pricking the flesh with a sharp instrument. Maguey (agave) spines are the tool most frequently mentioned in the historical texts, though slivers of obsidian and special perforators made from a spike-shaped piece of sharpened bone were also used. (Incidentally, Quetzalcoatl, the First Priest, is often shown in the codices holding a bone perforator or two.) From what I’ve read, it seems that maguey spines were particularly associated with piercing the ears and the legs, probably because their large size would be sufficient to draw blood from the legs. The individual would pierce himself or herself in the chosen location, and once the thorns were sufficiently bloodied, would carefully arrange them on a bed of cut fir boughs, or stick them into a ball of dried grass.
Alternatively, the Aztecs would nick their earlobes with an obsidian knife, and the blood would be allowed to drip on the ground, be sprinkled into a fire, or flicked towards the sun, symbolically giving the life-energy to Tonatiuh.
Finally, there was a final type of personal blood offering, that of passing straws or cords through the body. This rather severe form of autosacrifice was a multi-step process. The person would first select a place to pierce. In the texts I’ve read, the tongue seems to be the most common choice for this kind, though the ears, legs, and possibly penis were used as well. (I haven’t the slightest idea of how that last one worked, it’s definitely not something the Spanish friars would’ve recorded the details of!) Then they would poke a hole with a sharp sliver of obsidian, and pull a number of straws or thin cords through the hole. This sacrifice was typically done in a temple or at the side of the road. Wherever it was done, the bloodied straws were left behind as offerings. Interestingly, this practice was apparently only done on days that had a proper sign according to the ritual calendar (tonalpohualli), but I’ve never come across what daysigns those were. Finally, this practice of drawing straws is usually listed as a priestly activity, not something done by ordinary people, though occasionally the nobility appear to have done it as well. Priests who did this often were obvious, as their tongues would be extremely scarred, damaged to the point where they were said to have had difficulty in speaking.
Quetzalcoatl Holding Bone Perforators, Codex Borgia