This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Miguel Leon-Portilla's study of Aztec thought and culture situates the day signs within the wider Nahua concept of tonalli, a documented belief that the day sign under which a person was born genuinely shaped that person's fate and inner character, not a minor superstition but a structuring idea across Nahua religious and social life.
That documented cultural weight matters for a tonalpohualli day sign entry because it means a sign's meaning was not merely a divinatory label but bound up with real Nahua ideas about personal identity and destiny, and an entry records that wider conceptual context, tonalli, alongside the sign's specific documented fate or character, as two connected but distinct facts.
A tonalpohualli day sign entry therefore records both a sign's specific documented associations and, where the sources allow it, its place within this broader Nahua understanding of fate, since Leon-Portilla's own research treats the two as genuinely inseparable in Nahua thought itself. Recording that connection is part of describing the day sign system honestly rather than reducing it to a simple lookup table of fixed meanings.
Leon-Portilla's account also draws on surviving Nahuatl language sources directly, giving an entry a documented basis for describing tonalli in the tradition's own terms rather than through a later outside gloss placed over an unfamiliar concept.