The Four Pillars of Destiny (commonly known as *Bazi*, literally "Eight Characters") is an established Chinese astrological concept. It posits that a person’s destiny can be mapped by assigning two sexagenary cycle characters (one Heavenly Stem and one Earthly Branch) to the exact year, month, day, and hour of their birth, resulting in four distinct "pillars".
The conceptual foundation of Bazi traces back to the Han Dynasty (206 BCE – 220 CE), emerging from correlative cosmology that linked celestial phenomena with terrestrial human affairs. The fundamental mechanism of stem-branch chronometry (pairing stems and branches) can be historically verified through oracle bone inscriptions from the Shang Dynasty (c. 1600–1046 BCE).
The formal systematization of astrology using three pillars (year, month, day) was pioneered by the Tang Dynasty scholar Li Xuzhong (761–813 CE). However, the definitive expansion to four pillars—by incorporating the hour of birth and centering the analysis on the Day Master (日主)—was established by the Song Dynasty master Xu Ziping (960–1279 CE). His methodological reforms are continuously studied through the seminal text *Yuanhai Ziping* (渊海子平).