He Hun (合婚) means joining the marriage, and the practice is exactly what the name suggests: two birth charts are laid side by side and compared. What is less often explained is that there is no single agreed method.
The four methods
- Year animal — the popular method. Coarse: one character per person.
- Spirits and sha — checks for specific markers in each chart. Rules vary heavily between schools.
- Nayin element — compares the element of each year pillar pair. A distinct, self-contained method.
- Full four pillars — the most elaborate. Weighs the Day Masters, the Ten Gods and elemental balance together.
Why the methods disagree
These methods were developed in different periods and answer slightly different questions. A pair can be excellent by year animal and poor by nayin, or the reverse. This is not a bug in the tradition; it reflects that several independent systems accumulated under one name.
The nayin method, for instance, works only from the year pillars, while the four-pillar method can find a strong Day Master connection that completely overrides a poor year-animal match. Which one a reader reaches for is a judgement, not a calculation.
What to be sceptical of
Be wary of any tool that returns a single compatibility percentage without showing its working. Sites optimised for social sharing tend to collapse four incompatible systems into one number, and the number means very little. A reading that shows you its calculation is worth more than one that only shows you its conclusion.
How to use a compatibility reading
- Read the individual factors, not just the total.
- Check whether difficulty concentrates in one area or spreads across several.
- Treat any finding as a topic to discuss, not a conclusion about the relationship.
What the systems actually agree on
Not much, in detail — but they share a premise worth keeping: compatibility is about how two configurations interact, not about whether two people are similar. Two charts with the same dominant element can be worse together than two that complete each other. That is the one thing the traditional methods consistently assume.
Why the scores disagree
The four methods were developed in different periods and answer slightly different questions. The nayin method works only from the year pillars, while the four-pillar method can find a strong Day Master connection that overrides a poor year-animal match entirely.
Which one a reader reaches for is a judgement, not a calculation — which is why two competent readings can differ.