Jiazi Sexagenary Cycle

The Jiazi sexagenary cycle is formed by sequentially pairing the ten Heavenly Stems with the twelve Earthly Branches to create a sixty-term repeating cycle, and is one of ancient China's most important temporal measurement systems. Stem-branch day-recording was already extensively used in Shang-dynasty oracle-bone inscriptions, while stem-branch year-recording was formally established in the Western Han period, with the Taichu calendar promulgated in the first year of Emperor Wu's Taichu era (104 BCE) serving as an important institutional milestone. The cyclical recurrence of the sixty Jiazi terms was not only used to record years but was also endowed with philosophical meaning regarding the waxing and waning of yin-yang and the circulation of the Five Elements, becoming the basic temporal unit for later metaphysical calculations of major luck periods and annual flows.

Key Figures

Sima Qian — presided over the compilation of Shiji, whose 'Lishu' and 'Tianguanshu' systematically recorded ancient calendrical science and the stem-branch system; Luoxia Hong — Western Han astronomer who participated in formulating the Taichu calendar, establishing the calendrical framework with the first month as the new-year beginning and stem-branch year-recording

Important Works

Taichu Calendar — China's first relatively complete calendar, establishing the official status of stem-branch year-recording; Huainanzi · Tianxun — detailed records of the correspondences between stems and branches, the sixty Jiazi terms, and musical tones, directions, and seasons

Historical Significance

The Jiazi sexagenary cycle provided metaphysics with a precise temporal coordinate system; Bazi charting takes the stem-branch combinations of the birth year, month, day, and hour as its core data. The sixty-term cycle establishes a computable mathematical relationship between personal destiny charts and cosmic time, marking the key turning point at which metaphysics moved from philosophical speculation to technical deduction.