How the Stems and Branches Pair to Form Pillars

If you are new to Ba Zi, also known as Chinese Astrology, this is some very basic information to get you started. One of the names used for this system is Four Pillars of Destiny.

The Four Pillars are derived from a person’s birth information: year, month, day, time. Each pillar is made up of a Heavenly Stem and an Earthly Branch. Each pillar is a shorthand description of a type of process or potential.

The Heavenly Stems are on the top of a pillar, while the Earthly Branches are on the bottom. Let’s use the Water Monkey pillar as an example.

When we say “Water Monkey” we are talking about Ren (yang Water) over Monkey (yang Metal).

壬	yang Water
申	Monkey

The polarity, meaning yin or yang, of stem and branch must match. There is no yin Water Monkey. Since Monkey is yang Metal, the stem has to be yang too.

Each of the six yang branches (Rat, Tiger, Dragon, Horse, Monkey, Dog) pairs with any of the 5 yang stems. For example, there are five possible Monkeys. This is true for every yang branch.

甲	yang Wood	丙	yang Fire	戊	yang Earth	庚	yang Metal	壬	yang Water
申	Monkey	申	Monkey	申	Monkey	申	Monkey	申	Monkey

When we say Water Rooster, we are talking about yin water (Gui) over Rooster (yin Metal).

癸	yin Water
酉	Rooster

Because the polarity of stem and branch must match, there is no yang Water Rooster. Since Rooster is yin metal, the stem has to be yin too.

Each of the six yin branches (Ox, Rabbit, Snake, Sheep, Rooster, Pig) pairs with any one of the five yin stems. For example there are five possible Roosters.

乙	yin Wood	丁	yin Fire	己	yin Earth	辛	yin Metal	癸	yin Water
酉	Rooster	酉	Rooster	酉	Rooster	酉	Rooster	酉	Rooster

Following this logic, there are 60 pillars in a cycle that repeats infinitely. These 60 pillars begin with Wood Rat and end with Water Pig.