Decade phases: which way they run and when they start

In Four Pillars of Destiny (BaZi), the natal chart is fixed at birth, and life is set against it in stretches of ten years called decade phases, each written as one stem and one branch. The decade phases run in forward or reverse sequence from the month pillar, by the polarity of the year stem and the person’s sex. The first one begins at a starting age counted from the days between birth and the next solar term that begins a month (in reverse sequence, the last one before birth).

Decade phases use the chart’s own method

The True Interpretation of Ziping (子平真诠; Qing dynasty, 18th century) puts it plainly:

论运与看命无二法也。

Our translation: Looking at the decade phases and looking at the natal chart are one method, not two.

To look at the natal chart, the four pillars are set against what the month branch favors and disfavors; to look at a decade phase, its stem and branch are set against what the chart favors and disfavors. So decade phases are not a separate study: roots, Day Master strength and structure all apply to them unchanged.

The True Interpretation of Ziping · On the Decade Phases

The original notes to Dripping Heavenly Marrow (滴天髓) offer an image: the Day Master is yourself, the other characters of the chart are the boats, horses and attendants traveling with you, and a decade phase is the place you have reached. A place is a matter of ground, so in a decade phase the branch weighs more, though the stem still counts. Dripping Heavenly Marrow Elucidated (滴天髓阐微; Qing dynasty, 19th century) agrees, and adds that a decade phase is best when its stem and branch generate and support each other.

Dripping Heavenly Marrow · Annual and Decade Phases, original notes; Dripping Heavenly Marrow Elucidated · Annual and Decade Phases

Decade phases run from the month pillar

The decade phases start from the month pillar and follow the cycle of sixty stem-and-branch pairs one step at a time. In forward sequence they take the pairs after the month pillar in turn; in reverse sequence, the pairs before it. With a Yang Fire Tiger month pillar, for example:

• Forward sequence: Yin Fire Rabbit, Yang Earth Dragon, Yin Earth Snake, Yang Metal Horse …
• Reverse sequence: Yin Wood Ox, Yang Wood Rat, Yin Water Pig, Yang Water Dog …

So check the month pillar first. The months follow the solar terms, and a birth near the start of a month can change the month pillar and, with it, every decade phase; see the lesson on setting up the four pillars.

Forward or reverse

This series follows the common rule, by the polarity of the year stem and the person’s sex:

The year stem is set at the Start of Spring. If you were born in January or early February, first check that your year pillar has been set by the Start of Spring.

When the first decade phase starts

By the common convention, this age is found by counting days. In forward sequence, count from the moment of birth to the next solar term that begins a month; in reverse sequence, count back from the moment of birth to the last such solar term before it. Three days count as one year, one day as four months, and one two-hour period as ten days. This is a conventional conversion, not an exact rule. The result is the approximate age at which the first decade phase begins, the starting age; after that, a new decade phase begins every ten years.

For example, someone in forward sequence meets the next solar term fifteen days after birth. Fifteen days count as five years, so the first decade phase starts at about five, the second at fifteen, the third at twenty-five, and so on. This gives an approximate age; to fix it to the month, look up the moment that solar term begins in a perpetual calendar.

Before the first decade phase begins, no decade phase is running. Neither the month pillar nor the first decade phase stands in for those years; an annual phase that falls in them is set straight against the natal chart.

Try it on your chart

1. Write down your year stem and, using the table above, see whether your decade phases run in forward or reverse sequence.
2. From the month pillar, write out the stems and branches of your first eight decade phases.
3. Using a perpetual calendar, count the days: in forward sequence, from birth to the next solar term that begins a month; in reverse sequence, from the last such solar term to birth. Three days count as one year; work out your approximate starting age.
4. Beside each decade phase, write the age at which it starts, ten years apart.
5. Find the decade phase you are in now. If you have not reached your starting age, note that you are before the first decade phase.
6. Keep each decade phase for the next lessons, to be set against the natal chart.

See also: Setting up the four pillars: solar months, the year boundary and the midnight hour

See also: How a decade phase meets your chart

See also: Decade phases and your roots: support supplied, support struck

See also: The annual phase and its decade phase