Synastry & Affinity

Before going further, three things need to be clear:

5.1.1Three technical routes into synastry

5.1.2What synastry actually did in pre-modern society

Traditional matchmaking was never only a matter of “do they fit”. It carried four social functions:

An important insight: seen this way, traditional matchmaking looks less like a way of predicting how a marriage would turn out and more like a “communication tool between families”. That point is central to how we should understand its place today.

5.2.1The “six marriage rites” of the Zhou — the Yili's “Shi Hun Li”

The complete procedure of a marriage in ancient China was called the “six marriage rites”; it is first recorded in the Yili, in the chapter “Shi Hun Li”:

The key point: step 2, asking the name, obtained the birth date and hour; step 3, announcing the auspicious result, settled the matter by divination. This was China's earliest institution of matchmaking — not a folk superstition but a formal procedure written into the ritual canon.

How asking the name was done: once the groom's envoy had the woman's name and birth date, he returned home. There the Yili records that “the host laid out mats and tables in the ancestral temple and bowed to welcome him outside the gate”, after which the divination was performed. Only an auspicious omen was followed by the rite of announcing the auspicious result.

5.2.2Han and Tang: from divination to “reading the eight characters”

• –

  Han dynasty: matchmaking relied chiefly on divination (turtle shell, yarrow stalks) or other means; no systematic “destiny-arts matchmaking” had yet appeared.

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  Wei, Jin and Northern and Southern dynasties: family rank was all-important, and a marriage was weighed by social standing far more than by fate.

• –

  Tang dynasty: with the rise of Bazi — Li Xuzhong's “three pillars” — matchmaking began to be framed in destiny-arts terms. Late-Tang marriage contracts recovered from Dunhuang (such as the Youxian Pre-Marriage Contract and Li Kan and the Yang Family's Marriage Contract) already carry the set phrase “the two families join in harmony, kin for generations”.

• –

  The Tang marriage-contract format (Dunhuang manuscript P.3350 and others):

On a certain year, month and day, the family of [X] respectfully offers ceremonial gifts and announces to the household of [Y]:
We humbly acknowledge your esteemed family's consent to give your daughter to our son,
and respectfully cite the *Book of Songs*: “a modest and retiring maiden, a fit mate for a gentleman”…

5.2.3Song, Yuan, Ming and Qing: matchmaking comes fully into its own

Key sources:

• –

  Sanming Tonghui, volume 12, carries chapters such as “on marriage between men and women”

• –

  Yuanhai Ziping contains a dedicated chapter, “on marriage”

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  Popular “almanacs” (tongshu, the yellow calendar) all came with a matchmaking table appended

5.2.4From the Republic to today: a required step becomes a cultural topic

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  Before the Republic: matchmaking was a necessary stage of marriage. If the charts did not “fit”, the match could collapse outright.

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  After the 1950s: the Marriage Law established freedom of marriage, and matchmaking ceased to be a legal or socially required step.

• –

  Today: matchmaking has become a cultural ritual before the wedding, a playful exchange between a couple, or a traditional family concern.

Where synastry belongs: treat it as “a display of traditional marriage custom and an entry point for talking about a relationship”, not as “a tool for predicting whether a marriage will succeed”. That is both true to the cultural record and unlikely to mislead.

Zodiac matchmaking is the best known — and the simplest — form of synastry. It rests on the relations between the twelve Earthly Branches.

5.3.1The basic relations at a glance

5.3.2Six Combination (six pairs, the most auspicious)

The verse: “Zi-Chou, Yin-Hai and Mao-Xu combine; Chen-You, Si-Shen and Wu-Wei agree.”

The principle: Six Combination relates the twelve branches “one inside, one outside” on the dial. Zi (due north) sits beside Chou (north by east), yet tradition explains the twelve pairs as the positions of the sun-and-moon conjunction — the two bodies on the same celestial longitude — which is why it is also called “the combination of sun-and-moon conjunction”.

5.3.3Three Harmony (four groups, a strong combination)

The principle: Three Harmony links branches three places apart (120°) on the dial, an equilateral triangle that marks the strongest combination of an element.

The verse: “Shen-Zi-Chen combine into Water, Hai-Mao-Wei into Wood, Yin-Wu-Xu into Fire, Si-You-Chou into Metal.”

5.3.4The six Clashes (six pairs, the most inauspicious)

The principle: the six Clashes are branches set directly opposite each other — six places apart, or 180°.

5.3.5The six Harms (six pairs)

A way to remember them: each Harm pair stands five or seven places apart on the dial, and each of two branches that clash harms a member of the other's Three Harmony group. Take the clash of Zi and Wu: Wu's Three Harmony is Yin-Wu-Xu, and Zi harms Wei — Wei forming one half of that group — which is why Zi and Wei harm each other.

5.3.6The three Punishments (three groups, plus self-punishment)

The verse: “Yin punishes Si, Si punishes Shen, Shen punishes Yin; Chou punishes Xu, Xu punishes Wei, Wei punishes Chou; Zi punishes Mao, Mao punishes Zi; Chen, Wu, You and Hai punish themselves.”

5.3.7The folk “zodiac matchmaking verses”, examined

The matchmaking verse most widely repeated in folk tradition:

The white horse fears the black ox; Goat and Rat are finished at once. Snake and Tiger cut like a knife; Dragon and Rabbit exchange tears. The golden Rooster fears the jade Dog; Pig and Monkey never reach the end.

Line by line:

The conclusion: all six lines describe Harms — not Clashes at all.

⚠️ Three points that have to be understood:

• 1.

  This is one folk formulation of the Harms, not the whole of matchmaking. Many people know only this verse and conclude that “a Harm in the charts rules out marriage” — a serious overgeneralisation.

• 2.

  Versions of the verse differ completely from region to region. One version has Snake and Monkey pairing well; another has them clashing. One has Dragon and Tiger fighting; another has them combining. That is evidence in itself that these verses are regional folk belief with no unified theoretical basis.

• 3.

  Orthodox destiny-arts texts such as Sanming Tonghui do not judge by the zodiac animal alone. The zodiac animal is one character — the year branch — out of eight in a Bazi chart. Deciding a marriage by zodiac animal means letting the year of birth stand for a whole life. Logically, that does not hold.

A note for the reader: these verses are folk belief, not orthodox theory, and cannot serve as a basis for judgement; used otherwise they easily cause needless distress.

Bazi synastry reads how the two sets of Four Pillars interact with each other, which is far more involved than zodiac matchmaking.

5.4.1Five dimensions traditional synastry looks at

5.4.2The Day Pillars: the core of synastry

Between the day stems (Ten Gods interaction):

The five stem combinations and what they form:

A note: some of these traditional names — “the Combination of Licentiousness”, “the Combination of Heartlessness” — carry the prejudices and gender assumptions of their time and should not be reused. A neutral technical description serves better.

Between the day branches (the spouse palaces):

5.4.3Complementary Useful Gods

This is the best-grounded method in synastry:

If A's Useful God is “Fire”,
and Fire is strong in B's chart (or B's day pillar carries Fire),
tradition holds that B can “help” A.

How to work through it:

• 1.

  Cast both people's charts separately

• 2.

  Determine each person's Useful God separately (see Chapter 02, §2.3.6)

• 3.

  Check whether the other person's chart contains much of the element to which the Useful God belongs

• 4.

  If each person's Useful God is supplied by the other's chart, this is called “exchanging Useful Gods” and is the most favorable combination of all

This is the most internally coherent method in synastry, because it defines “compatibility” as complementary energy rather than as a simple “your zodiac animals clash”.

5.4.4The complementarity table

The “missing element” claim, examined:

Folk advice often runs, “whatever element is missing, add it”. That is a one-sided reading.

The sound understanding is this:

• –

  What is missing is not necessarily what is needed — in a strong chart, the absent element may be one that should be kept in check

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  What matters is the Useful God, not what is “missing”

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  Charting software must distinguish “missing” from “Useful God” — that distinction is a mark of professionalism

5.4.5The traditional “five to seek and five to avoid”, as set out in Sanming Tonghui

The traditional “five to seek”:

The traditional “five to avoid”:

⚠️ A note for the rational reader: the “five to avoid” above is offered as cultural background only, and should not be turned into conclusions such as “you two should not marry” or “there is a risk of divorce”.

This method applies the Eight Mansions (Ba Zhai) feng shui system to matchmaking; it and Bazi synastry are two independent systems.

5.5.1Calculating the life trigram

East Four Life-Groups: Kan, Li, Zhen, Xun. West Four Life-Groups: Qian, Kun, Gen, Dui.

The formula for the life trigram (a simplified version):

For men:

Life-trigram number = the remainder when (100 − the last two digits of the birth year) is divided by 9

For women:

Life-trigram number = the remainder when (the last two digits of the birth year − 4) is divided by 9

Which trigram each remainder gives (the nine palaces of the Luoshu):

Note: what to do with a remainder of 5 is disputed. The common practice assigns men to Kun and women to Gen, both West Four. Different schools handle it differently.

5.5.2The matching rules

The logic behind Eight Mansions: people in the same group are said to carry a “qi field” of similar frequency, so same group with same group is the more harmonious pairing.

A scholarly note: the standard use of the Eight Mansions system is domestic feng shui — siting the door, the main bedroom and the stove. Applying it to matchmaking is a later extension and was never mainstream in the traditional literature.

5.5.3The “eight wandering-year stars” of Eight Mansions matchmaking

Eight Mansions theory holds that a life trigram stands in one of eight relations to a direction — the eight wandering-year stars:

How it is used for matchmaking: check whether the two life trigrams stand to each other as Sheng Qi, Tian Yi or Yan Nian — the preferred combinations for a marriage.

Once more, for emphasis: this whole system belongs to traditional feng shui and the arts of calculation. It has no empirical scientific basis and is presented here as cultural background only.

5.6.1From “fated” to “structural”

The traditional view: affinity is “fated”, “decided in Heaven”; whether the two charts fit determines whether the two can be together.

The modern view: what we call “affinity” can be taken apart into two parts:

“Encounter” is probability; “sustaining” is a skill.

5.6.2Relationship matching through the lens of psychology

The factors that modern relationship psychology studies:

The decisive contrast: traditional synastry looks at a combination of birth times; modern research looks at patterns of interaction. The two are not on the same plane at all.

5.6.3What synastry can legitimately be used for

If synastry must be given a “useful” place, it might be one of these:

What it must never be used for:

• –

  ❌ Deciding whether to marry or to break up

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  ❌ Passing a death sentence on an existing relationship

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  ❌ Serving as an excuse to avoid talking about a problem

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  ❌ Manufacturing anxiety (“our charts clash — is it over?”)

5.6.4The “self-fulfilling prophecy” effect

This is the psychological effect that matters most in synastry:

Tell a couple that “your charts clash and the marriage will not be harmonious”, and in daily life they may:

• 1.

  become more alert to conflict (“there it is — the clash”)

• 2.

  invest less (“it is doomed anyway”)

• 3.

  attribute ordinary disagreements to “fate” instead of resolving them

The result: the relationship really does get worse.

This is one of the main mechanisms by which destiny-arts readings appear to come true, and the reason synastry conclusions need to be handled with particular care.