The System Behind Ten Separate Entries

This entry exists to hold the system as a whole, distinct from the ten individual stem entries already recorded elsewhere in the atlas, because a stem in isolation, Jia or Gui on its own, means little outside the structure that relates all ten to each other and to the Twelve Earthly Branches. The pairing logic is what carries most of the system's explanatory power: knowing that Jia and Yi both belong to Wood, with Jia yang and Yi yin, tells a practitioner of Bazi astrology or Chinese medicine considerably more than knowing Jia's bare identity, since compatibility, conflict and transformation between stems in a chart are read off exactly this shared-phase, opposite-polarity structure.

The stems also interact with Chinese medicine's body correspondences and with feng shui direction systems, though those applications elaborate the base cosmology recorded here rather than replacing it. Because oracle bone evidence places the ten-day naming convention centuries before any of the divinatory or medical uses that made the stems famous outside China, the atlas treats the calendrical function as the historically attested core and the fate-calculation uses as a later, well documented elaboration built on top of it, a sequence worth keeping straight given how often popular accounts present Bazi astrology as the stems' original purpose rather than one of several systems layered onto a much older calendrical device.