Chinese astrology and Ba Zi

Where they come from. The cycle of the ten heavenly stems and the twelve earthly branches already appears on the oracle bones of the Shang dynasty, in the second millennium BC: it was then used to count days. The twelve animals joined the branches by the third century BC at the latest: this is popular Chinese astrology, that of the year sign. Ba Zi is its learned form. It took shape under the Song, in the tenth century, with Xu Ziping, who centered the chart on the day of birth.

What they draw on. The date and time of birth, read in the Chinese solar calendar. The year gives the animal and its element; the hour gives the ascendant, a second animal. Ba Zi goes further: four pillars — year, month, day, hour — each bearing a stem and a branch, making eight characters in all: ba zi. Each belongs to one of the five elements, Wood, Fire, Earth, Metal, Water, in yin or in yang.

What they are for. The animal of the year tells the character's social face; that of the hour, their more intimate side. The Ten Gods, drawn from how each of the eight characters relates to the day stem, shed light on the great areas of life: what supports them, what they express, what they earn, what gives them structure, and their peers. Ba Zi takes stock of their energy: what nourishes them, what drains them, the element missing or in excess. The luck pillars, ten years each, divide life into seasons, and each year adds its own color.

The Chinese year turns over in early February, not at the Lunar New Year: a child born in January belongs to the animal of the previous year.