Boys destined for the priesthood, generally though not exclusively drawn from noble families, entered the calmecac, a boarding school attached to a major temple, where they were raised apart from ordinary Mexica life under strict discipline. Sahagun's informants describe a regimen of predawn rising, cold ritual bathing, fasting, sweeping and maintaining the temple precinct, and regular bloodletting from the ears, legs and tongue as an ongoing personal devotional practice rather than an occasional rite, alongside instruction in the sacred and solar calendars, the proper conduct of ceremonies, oratory, and the pictorial writing used to record ritual and historical knowledge.
The tlamacazqui title itself, built from a root meaning something close to giving or distributing, reflected the priesthood's role as intermediary, giving offerings to the gods on the community's behalf and, in Aztec understanding, receiving in turn the gods' favor and instruction to pass back to the people. Successful trainees could progress through a graded hierarchy of specialized offices distinguished by particular duties, among them the tlenamacaque, fire priests responsible for maintaining sacred fires and conducting fire-related rites central to major festivals.