TL;DR: In Mai Hoa Dịch Số, the trigram that does NOT contain the moving line is the thể, representing the querent; the trigram that CONTAINS the moving line is the dụng, representing the matter asked about. Auspiciousness or inauspiciousness is read through the five elemental relationships between thể and dụng: dụng generating thể, mutual harmony, and thể overcoming dụng are favorable, while thể generating dụng and dụng overcoming thể are unfavorable (Mai Hoa Dịch Số, volume 2). This is a common convention, not an absolute truth, and some online summaries state it in reverse, so it is best to check directly against the original page.
What is Mai Hoa Divination and where do body and function sit in the reading?
Mai Hoa Divination (Vietnamese: Mai Hoa Dịch Số) is an applied branch of the Zhouyi (the Book of Changes), one that uses numbers or outer circumstances as the material for casting a hexagram, then interprets a specific situation. The method is tied to the name of Shao Kangjie of the Song dynasty, and its name comes from the anecdote in which he watched two sparrows quarrel on a plum branch and read an omen from it. What sets it apart from a purely philosophical reading of the Book of Changes is that it turns the classic into a tool for interpreting situations: there is a question, a hexagram is cast, and the direction of events is then read through that hexagram.
A hexagram of the Book of Changes consists of six lines, built from two three-line trigrams: the inner trigram below and the outer trigram above. When a hexagram is cast, there is always a moving line. It is precisely the position of the moving line that determines which trigram is the body and which is the function. This is the key step, because the entire later discussion of fortune and misfortune rests on this body and function pair.
The rule for identifying body and function
The rule is written exactly as follows: the trigram that does NOT contain the moving line is the body, representing the person asking; the trigram that CONTAINS the moving line is the function, representing the matter being asked about. If the moving line falls in the inner trigram (the lower three lines), then the inner trigram is the function and the outer trigram is the body. If the moving line falls in the outer trigram (the upper three lines), then the outer trigram is the function and the inner trigram is the body. This way of identifying them follows Mai Hoa Dịch Số (attributed to Shao Yong), opening section, volume 1 and volume 2, Chinese Wikisource edition.
It should be noted that some summary passages found in online search results state this rule backwards, claiming that the trigram containing the moving line is the body. That wording does not match the general interpretive tradition, where it is stated clearly that the body is the trigram not containing the moving line. Readers should check the original page directly rather than trust a shortened summary, because simply swapping body and function reverses every conclusion about fortune and misfortune.
The eight trigrams with their Earlier Heaven numbers and five phases
To discuss generating and overcoming, you first have to know which phase each trigram belongs to. Mai Hoa uses the Earlier Heaven numbers to convert a number into a trigram, and the table below is the core that the calculation rests on.
| Trigram | Earlier Heaven number | Five phases | Direction |
|---|---|---|---|
| Qian | 1 | Metal | Northwest |
| Dui | 2 | Metal | West |
| Li | 3 | Fire | South |
| Zhen | 4 | Wood | East |
| Xun | 5 | Wood | Southeast |
| Kan | 6 | Water | North |
| Gen | 7 | Earth | Northeast |
| Kun | 8 | Earth | Southwest |
This table matches the way the directions of the eight trigrams are presented in the Book of Changes: Kun governs the Southwest, Gen the Northeast, Zhen the East, Xun the Southeast, Li the South, Dui the West, Qian the Northwest, Kan the North (Shuo Gua Zhuan, chapter 5, Chinese Wikisource edition; Mai Hoa Dịch Số (attributed to Shao Yong), opening section, volume 1 and volume 2, Chinese Wikisource edition). The five-phase assignment of the trigrams is a shared foundation, not exclusive to Mai Hoa, since methods such as Liu Yao (Six Lines) use it too. The five-phase properties of the eight trigrams, and identifying which trigram is upper and which is lower, are the step that shapes the overall picture before going into detail.
Why the Earlier Heaven numbers matter
The Earlier Heaven numbers are the bridge between the number the user enters and the trigram. The same set of numbers always yields the same hexagram, so repeatability is a feature of the method, not a flaw. In the interpretive tradition, if the same hexagram comes up repeatedly, that is a sign that the questioner's mind is very clearly attached to the matter, not that the system is stuck. Besides entering numbers, Mai Hoa also allows casting from outer circumstances, that is, taking an omen from the first sign to appear around the questioner at the very moment the thought arises. This is exactly the spirit of the plum branch anecdote.
How do the five generating and overcoming relations between body and function reveal fortune or misfortune?
This is the central question of the body and function method. Once it is established which trigram is the body and which is the function, the reader compares the five phases of the two trigrams. There are exactly five possibilities, and each carries a different implication. The table below gathers the five relations together with the level of fortune or misfortune usually assigned to them.
| Relation | Five phases | Meaning | Level of fortune or misfortune |
|---|---|---|---|
| Function generates body | Function generates into the body | The matter comes to nourish the person, outside support is present | Fortunate, favourable |
| Harmony of peers | Same phase | Person and matter are in step, no clash | Fortunate, smooth |
| Body overcomes function | Body overcomes out to the function | The person controls the matter | Fortunate, all things go well |
| Body generates function | Body generates into the function | The person spends strength on the matter, gains little, loses much | Unfortunate, adverse |
| Function overcomes body | Function overcomes into the body | The matter presses on the person, pressure from outside | Unfortunate, caution needed |
The levels of fortune and misfortune for the five relations follow Mai Hoa Dịch Số, volume 2: 體克用，諸事吉；用克體，諸事凶。體生用，有耗失之患；用生體，有進益之喜。體用比和，則百事順遂. That is, when the body overcomes the function all matters are good; when the function overcomes the body all matters are unfortunate; when the body generates the function there is a risk of loss; when the function generates the body there is joy at a gain; when body and function are in harmony of peers, a hundred matters go smoothly. Some later documents add the condition that body overcoming function is only good when the questioner actually takes action; this is an added interpretation, not present in the original text of volume 2.
A compact way to remember it is to look at the direction of the generating flow and the overcoming flow. When the flow moves into the body (function generates body), the body benefits. When both sides are of the same phase (harmony of peers), the situation is balanced and tends to go smoothly. When the body overcomes the function, the body wins and things go well. Conversely, when the body generates outward to the function, the body is drained, and when the function overcomes the body, the body is pressed down from outside. This is the common reading in the interpretive tradition.
Do not read fortune and misfortune as a verdict
It should be said plainly that the five relations above give a tendency, not a fixed outcome. The same body and function pair, placed at a different time or in a different season, will have a different strength in each of the two phases. A Metal trigram is prosperous in autumn and weak in summer, and the level of fortune or misfortune shifts accordingly. The old texts are also not entirely consistent on whether timing needs to be factored in. The interpretive tradition holds that timing must be combined in order to judge the tendency, while many introductory documents stop at the body and function pair alone. Learners should know both approaches, and know which one they are following.
What role do the mutual hexagram and the changed hexagram play in the three-stage reading?
A Mai Hoa hexagram is not only the original hexagram. A full reading is usually divided into three layers: the primary hexagram, the mutual hexagram and the changed hexagram. The primary hexagram is the one cast at the start, showing the present situation and the main body and function pair. The mutual hexagram is built from the middle lines of the primary hexagram, used to illuminate the inner developments, the things that do not show immediately. The changed hexagram is the one produced after the moving line changes, showing the direction of the ending and the later consequences.
These three layers correspond to three stages: beginning, process and outcome. When interpreting, an experienced reader usually reads the primary hexagram first to grasp the situation, then looks at the mutual hexagram to understand why events unfold as they do, and finally looks at the changed hexagram to judge the result. If the primary hexagram is good but the changed hexagram is bad, it means the start is favourable but caution is needed later. If the primary hexagram is bad but the changed hexagram is good, it means hardship lies ahead for now but there is a way out later.
The mutual hexagram is not an arbitrary extra
Some people treat the mutual hexagram as mere decoration, but in practice it has its own role. The mutual hexagram takes lines two, three and four as the inner trigram and lines three, four and five as the outer trigram, so it sits nested inside the primary hexagram, reflecting precisely the submerged part of the situation. In many cases the primary hexagram looks calm on the surface while the mutual hexagram reveals a clash, and that is where the reader should raise questions.
How do casting by number and casting by outer circumstance differ?
In the general interpretive tradition, Mai Hoa has two common ways of casting. The first is entering numbers, also called the number method, that is, taking a random number and converting it into the upper trigram, the lower trigram and the moving line. The second is observing outer circumstances, taking an omen from the first sign to appear around the questioner at the very moment the thought arises. The source for the numbers can be the current hour and minute, the serial number on the first banknote drawn from a wallet, the licence plate of the vehicle one is sitting in, or the page number of a book opened at random.
The two ways differ in that the number method gives stable and easily verifiable results, while the outer circumstance method depends heavily on the observer's ability and on the conventions of the person casting. This is also a point on which the schools disagree: some read additional outer correspondences around the moment of casting, others ignore them entirely and use only the hexagram. There is no common standard that forces one side. Learners should know that both exist and choose the approach that suits them, as long as they stay consistent within a single reading.
Is the attribution to Shao Yong certain?
Mai Hoa Dịch Số is usually attributed to Shao Yong, that is Shao Kangjie, a notable figure of the Song dynasty. He lived roughly from 1011 to 1077, with the courtesy name Yaofu (Tuo Tuo and other historians (1345), Song Shi, volume 427, Dao Xue Zhuan, Shao Yong Zhuan). He was famous as a cosmologist, historian, philosopher and poet with great influence on the development of Neo-Confucianism in the Song era. He was one of the most erudite men of his time, never took office throughout his life, and left behind an important cosmological work, the Huang Ji Jing Shi (Tuo Tuo and other historians (1345), Song Shi, volume 427, Dao Xue Zhuan, Shao Yong Zhuan).
Shao Yong lived in Luoyang from 1049 until his death; the Song Shi records that Sima Guang, Zhang Zai, Cheng Hao and Cheng Yi were among those who associated closely with him (Don J. Wyatt (2005), entry Shao Yong (1011-1077), Encyclopedia of Philosophy; Tuo Tuo and other historians (1345), Song Shi, volume 427, Dao Xue Zhuan, Shao Yong Zhuan). In the Song period there were two main directions in the study of the Book of Changes. Most scholars followed the school of meaning and principle, based on textual concepts and ethics. The other direction, the one Shao Yong pursued, leaned toward image and number (Justin Tiwald (revised 2025), Song-Ming Confucianism, Stanford Encyclopedia of Philosophy). What is notable is that the available documents only say Mai Hoa is attributed to him, not that he is its true author. This is a point that should be stated plainly: there is no certain evidence that Shao Yong himself wrote the method known today as Mai Hoa Dịch Số (Tuo Tuo and other historians (1345), Song Shi, volume 427, Dao Xue Zhuan, Shao Yong Zhuan). The attribution may be a later tradition, and readers should distinguish between the real historical figure and the work attributed to that figure.
What should be combined with a body and function reading to avoid error?
A common error is to look only at the body and function pair and conclude immediately, ignoring the mutual hexagram, the changed hexagram and timing. That approach gives a crude result and is easily wrong. A full reading should proceed in order: identify the moving line, separate body and function according to the correct rule that the trigram not containing the moving line is the body, compare the five phases to obtain the relation, and only then extend to the mutual hexagram and the changed hexagram to adjust the degree and the timing.
It should also be remembered that Mai Hoa is independent of Tử Vi (Vietnamese astrology). Tử Vi relies on the date and hour of birth to examine a whole life, whereas Mai Hoa relies on the question and on the numbers at the exact moment of asking, and answers only for one specific situation. In the interpretive tradition, the two are separate modules, one reading a birth chart, the other casting a hexagram of the Book of Changes. So do not mix Tử Vi criteria into a body and function reading, and do not use a Mai Hoa result to assert anything about an entire life.
The caveat to keep
However rigorous the method, the result is still a way of reading tendencies based on cultural convention, not a scientific forecast. It should not be used to assert anything certain about anyone's finances, health or destiny. Its value lies in helping the questioner look again at the situation and weigh things up before acting.
