TL;DR: The structure of a BaZi chart is determined first by the month order, then by examining the visible stems within the hidden stems to select the structure, giving priority to the primary qi. The Ten Gods are called Primary when their yin-yang polarity differs from the Day Master, and Secondary (or Seven Killings) when the polarity is the same; this must be distinguished from the Shen Sha. There are two ways to count the number of primary structures: Zi Ping Zhen Quan establishes eight structures based on the month order, while the ten-structure approach that separates primary and secondary is a presentation found in modern books.
How is a Bát Tự structure determined from the month order and stem transparency?
The structure is determined first and foremost by the month order, that is, the earthly branch of the month pillar, because the month branch governs the seasonal node of the birth season. Once the month order is identified, the analyst looks at which stem among the hidden stems of the month branch is transparent on the heavenly stems in order to choose the structure. The general principle is to examine the primary qi of the month order first, and only when the primary qi is not transparent does one proceed to the middle qi and then the residual qi.
Two matters need to be distinguished: determining the structure and choosing the useful god. The structure shows the overall architecture of the chart, while the useful god is the element needed to balance or support that architecture. This article focuses on structure; the selection of the useful god and the assessment of strength and weakness have been presented in separate articles within the same Bát Tự section.
Why must the month order be taken as the root?
The month order is the month branch, where climate and seasonal node govern the entire chart. No matter how strong a stem may be, if it is born in a month that controls it, that strength is also limited. Conversely, a weak stem born in the right season can be substantially supported.
The classification of structures is generally divided into two groups: ordinary structures (principal structures) and special structures (outer structures). Principal structures account for the majority of charts, while outer structures are less common. When a chart fits an outer structure, the analyst usually gives priority to analysing it as an outer structure first; if not, they move on to the principal structure.
How does stem transparency determine the structure?
A transparent stem is a heavenly stem that appears in the pillars and carries the element of a hidden stem within the month order. When a hidden stem of the month branch is transparent on the heavenly stems, the structure is established more clearly. If several hidden stems are transparent together, the priority principle is primary qi first, then middle qi, and finally residual qi.
For example, if the month branch is Dần, its hidden stems are Giáp, Bính and Mậu. If Giáp is transparent on the heavenly stems, the structure leans toward Wood; if Bính is transparent, it leans toward Fire; if Mậu is transparent, it leans toward Earth. In cases where no stem is transparent, the analyst relies on the primary qi of the month order to determine the structure, or examines other factors in the whole chart.
How many principal structures are there in Bát Tự?
The number of principal structures depends on the method of presentation. Tử Bình Chân Thuyên establishes only eight structures according to the month order: the four used in the forward manner, namely Tài, Quan, Ấn and Thực, and the four used in the reverse manner, namely Thất Sát, Thương Quan, Kiến Lộc Nguyệt Kiếp and Dương Nhận; within these eight structures, Tài and Ấn are not split into principal and secondary. The ten-structure method that separates principal and secondary (Chính Tài and Thiên Tài, Chính Ấn and Thiên Ấn) is a presentation found in modern books.
What are the Ten Gods and how do they relate to the Day Master?
The Ten Gods are the ten relationships between the Day Master and the other stems and branches, formed from five principal relationship pairs: Tỷ Kiếp, Thực Thương, Tài, Quan Sát and Ấn. In each pair, one god shares the same yin or yang as the Day Master and one god differs in yin or yang from the Day Master; the traditional naming is Chính when the yin or yang differs, and Thiên (or Thất Sát) when the yin or yang is the same.
The table below summarises the ten gods according to the site's core framework, cross-referenced with the example of a Day Master Giáp (yang Wood):
| God | Group | Relationship with the Day Master | Yin or yang relative to the Day Master | Example with Day Master Giáp |
|---|---|---|---|---|
| Tỷ Kiên | Tỷ Kiếp | same element as the Day Master | same | Giáp |
| Kiếp Tài | Tỷ Kiếp | same element as the Day Master | different | Ất |
| Thực Thần | Thực Thương | the Day Master produces this element | same | Bính |
| Thương Quan | Thực Thương | the Day Master produces this element | different | Đinh |
| Thiên Tài | Tài | the Day Master controls this element | same | Mậu |
| Chính Tài | Tài | the Day Master controls this element | different | Kỷ |
| Thất Sát | Quan Sát | this element controls the Day Master | same | Canh |
| Chính Quan | Quan Sát | this element controls the Day Master | different | Tân |
| Thiên Ấn | Ấn | this element produces the Day Master | same | Nhâm |
| Chính Ấn | Ấn | this element produces the Day Master | different | Quý |
Note that the Ten Gods should not be confused with the Thần Sát. The Thần Sát are a group of auxiliary stars such as Dịch Mã, Đào Hoa and Thiên Ất, and are not the ten stem relationships described above.
Characteristics of each group of principal structures
Quan Sát
Chính Quan is a relationship that controls the Day Master but differs in yin or yang, symbolising discipline, office and honour. Thất Sát also controls the Day Master but shares the same yin or yang, carrying a nature of pressure, competition and severity. Both require the Day Master to have enough strength to receive them, otherwise they become a burden.
Tài
Chính Tài is the wealth star that differs in yin or yang, representing stable income and accumulation. Thiên Tài shares the same yin or yang, representing unexpected sources of income, speculation and wide connections. The wealth star needs to be supported by production and not excessively seized by the rob wealth.
Ấn
Chính Ấn is the seal star that differs in yin or yang, symbolising learning, foundation and protection. Thiên Ấn shares the same yin or yang, leaning toward intuition, unconventional thinking and sometimes solitude. The seal star needs strength and weakness in harmony with the Day Master.
Thực Thương
Thực Thần is the god produced by the Day Master with the same yin or yang, governing nourishment, creativity and stability. Thương Quan differs in yin or yang, governing breakthrough, challenge and change. Both drain the Day Master, so they need the wealth star or the seal star to regulate them.
Kiến Lộc and Dương Nhận
Kiến Lộc is when the Day Master meets its own prosperity branch, symbolising a firm root qi. Dương Nhận is when the Day Master meets the strongest branch of its own element, carrying a fierce nature that needs to be controlled and transformed. According to Tử Bình Chân Thuyên, these two structures are among the eight structures and belong to the reverse-use group; the description of them as a "special group" is a presentation found in modern books.
Table of conditions for formation, destruction and the rescuing god
| Structure | Condition for formation | Condition for destruction | Rescuing god |
|---|---|---|---|
| Chính Quan | The Day Master has enough strength, the Quan star has Tài to produce it, and it is not controlled by Thương Quan | Thương Quan destroys Quan, the Day Master is weak and cannot bear it | The Ấn star controls Thương Quan, Tỷ Kiếp supports the Day Master |
| Thất Sát | Sát is controlled and transformed, the Day Master is strong or has Thực Thần to control Sát | Sát is strong and uncontrolled, the Day Master is weak | Thực Thần controls Sát, the Ấn star transforms Sát |
| Chính Tài | Tài is strong, the Day Master has enough strength, and it is not seized by the rob wealth | Tỷ Kiếp seize Tài, Tài is weak | The Quan star controls Tỷ Kiếp, Thực Thần produces Tài |
| Thiên Tài | Tài has a source, the Day Master is strong, and there is a Quan star in coordination | Tài is weak, Tỷ Kiếp are strong | The Quan star, Thực Thần |
| Chính Ấn | Ấn is strong, the Day Master is produced, and it is not destroyed by Tài | The Tài star destroys Ấn, Ấn is weak | The Quan star produces Ấn, Tỷ Kiếp supports the Day Master |
| Thiên Ấn | Ấn has a source, the Day Master is strong, and it is not destroyed by Tài | The Tài star destroys Ấn, Ấn is weak | The Quan star, Tỷ Kiếp |
| Thực Thần | Thực is strong, the Day Master has enough strength, and there is Tài to drain it | The kiêu thần seizes Thực, the Day Master is weak | The Tài star, Tỷ Kiếp |
| Thương Quan | Thương is controlled, the Day Master is strong, and there is Tài to drain it | Thương is strong and uncontrolled, the Day Master is weak | The Ấn star controls Thương, the Tài star drains Thương |
| Kiến Lộc | The Lộc god is strong, the Day Master holds the season, and there is Tài and Quan in coordination | Lộc is clashed and broken, Tài and Quan are too strong | The Quan star, the Tài star |
| Dương Nhận | Nhận is controlled, the Day Master is strong, and there is Quan Sát to control it | Nhận is strong and uncontrolled, the Day Master is weak | Quan Sát |
The table above is summarised according to the general principles recorded in classical Bát Tự texts such as Tử Bình Chân Thuyên and Tam Mệnh Thông Hội. For the Dương Nhận row, Tử Bình Chân Thuyên only mentions Quan Sát controlling Nhận; some modern books add Thực Thần. Books may differ in detailed interpretation, but the framework of conditions for formation and destruction is broadly similar.
Where do the formation and destruction of a structure come from?
When the five elements in a chart combine in a balanced way, the structure is considered formed. At that point, the useful god appears clearly and exerts its effect. Conversely, if the structure falls into a state of being destroyed, or falls into excess or deficiency, then life tends to meet many obstacles and storms.
Even so, even when a structure appears unfavourable, as long as a resolving factor or a remedy appears in the chart, the adverse effect can still be reduced. This shows that one should not conclude fortune or misfortune based solely on the name of the structure, but must examine the whole chart and the luck cycles.
According to Tam Mệnh Thông Hội, volume 2, chapter Luận Lục Hại, when examining harm one must base the judgement on the birth, prosperity, death and extinction and on the noble or base quality of the structure, concluding that the noble is noble in itself and the harm is harm in itself, the two do not cover each other. In other words, destruction and harm do not in themselves decide fortune or misfortune but depend on the specific structure.
Outer structures: when principal structures no longer fit
In some charts, the Day Master falls into a state of being too strong or too weak, making the application of a principal structure strained. Moving to an outer structure is the step to take at this point. Outer structures are not a set of rigid rules but a flexible approach based on the overall situation.
The dominant-element structure is a commonly encountered type of outer structure, appearing when all the stems and branches in the four pillars belong to a single element, or form a three-combination or three-meeting of that element, without being controlled by another element. For example, the case of pure Wood qi, named Khúc Trực Cách, occurs when the day stem is Giáp or Ất, born in a season when Wood is strong, with earthly branches consisting entirely of Dần, Mão and Thìn (the three-meeting of the East) or Hợi, Mão and Mùi (the three-combination Wood structure), and at the same time Canh, Tân, Thân and Dậu do not appear in the four pillars.
Other outer structures include the following structures, the transformation-of-qi structure, single-element attainment of qi, and two-god formation of image. Details of each type will be presented in the Tòng Cách dictionary entry and in separate in-depth articles.
Where the schools interpret differently
There are at least two notable points of difference between the schools.
First, Tử Bình Chân Thuyên uses the structure to determine the useful god, that is, from the architecture of the structure it infers the element needed for balance. Meanwhile, the support-and-suppress school separates the two matters: determining the structure is one step, and choosing the useful god according to the principle of supporting or suppressing is another step. This difference affects how the entire chart is interpreted.
Second, for months of mixed qi such as Thìn, Tuất, Sửu and Mùi, there are also many viewpoints on which stem to use in determining the structure. Some books give priority to the primary qi of the month branch, while others also examine the middle qi and residual qi if the primary qi is not transparent. This leads to results in determining the structure that may differ between the schools.
Practical application of the structure
In practice, correctly identifying the structure helps give suitable advice on the direction of development. For instance, if a person has Tài producing Quan but a weak self, or Thương Quan destroying Quan without control and transformation, then the safe solution is not to pursue high office. Conversely, when Thương Quan, Tài and Quan are all present in a harmonious architecture, with a strong self and a favourable luck cycle arriving, then that person may rise.
However, it should be remembered that the structure is only one part of the overall picture. The Đại Vận (major luck cycles), Tiểu Vận (minor luck cycles) and the interaction between the factors in the four pillars are the final deciding factors. Consulting an experienced expert is still necessary in order to obtain useful and accurate advice.
Points to note when interpreting structures
When interpreting structures, two extremes should be avoided: one is asserting absolute fortune or misfortune based only on the name of the structure, and the other is ignoring the structure to focus only on strength and weakness. The structure shows the architecture, strength and weakness show the power, and the useful god shows the balancing element. All three must be considered together.
In addition, classical texts such as Tam Mệnh Thông Hội emphasise that when examining harm one must base the judgement on the birth, prosperity, death and extinction and on the noble or base quality of the structure, that the noble is noble in itself and the harm is harm in itself, the two do not cover each other. This is an important principle for avoiding mistaken conclusions.
