TL;DR: The Dụng thần is the hào chosen to represent the main subject of the question, for example when asking about wealth then take the hào Thê Tài, when asking about work then take the hào Quan Quỷ. There is no fixed hào for every question, but the Dụng thần must be determined first and only then can sinh khắc and vượng suy be discussed. When the quẻ has two hào of the same type then priority goes to the hào động, then to the hào vượng tướng, and hào meeting Tuần Không or Nguyệt Phá are excluded. Quẻ Du hồn, Quy hồn and the cung of the quẻ do not change the Dụng thần but change the reading context, often suggesting movement and uncertainty. Some matters such as asking about things already clear, asking as a test, asking too many times about the same matter, or asking about things beyond one's scope of involvement are usually advised by the Lục Hào schools not to be brought to divination.
Dụng thần in Lục Hào (Vietnamese six-line divination): which line to read for which question, and why some matters should not be put to the hexagram
What is dụng thần in Lục Hào?
Dụng thần (the "useful spirit") is the line chosen to represent the main subject the querent wants to know about, and every step of interpretation afterwards revolves around this line. If the dụng thần is chosen wrongly, then even a correct reading of generation and restraint, of strength and weakness, is meaningless, because you are analysing a line that has nothing to do with the question.
In the Lục Hào system, each hexagram has six lines, and each line carries one of the six spirits: Huynh Đệ (Siblings), Tử Tôn (Offspring), Thê Tài (Wealth), Quan Quỷ (Officials and Ghosts), Phụ Mẫu (Parents), along with the Thế line itself. The interpreter must rely on the question to decide which line is the dụng thần, which is the nguyên thần (the source spirit), which is the kỵ thần (the restraining spirit), and which is the cừu thần (the enemy spirit). This is the first step and also the step that decides the accuracy of the entire hexagram.
It should be said plainly at once: this is a convention of the Lục Hào school, not the original text of the ancient Kinh Dịch (the Classic of Changes). The original Kinh Dịch has only 64 hexagrams with their hexagram statements and line statements, and no system of six spirits, six relations, or dụng thần. These concepts were added gradually over the generations, and are especially tied to the Nạp Giáp (Na Jia) tradition, which Kinh Phòng is regarded as having systematised early. Therefore, when reading material on dụng thần, one should know which school's material one is reading.
Why must dụng thần be determined before interpreting the hexagram?
Determining the dụng thần first is the only way to know which line is speaking about the matter being asked, and which line is merely background. A hexagram may contain a very strong line, but if that line is not the dụng thần, its strength does not answer the question.
The interpretive mechanism of Lục Hào rests on four relationships between the lines:
- Nguyên thần: the line that generates the dụng thần, symbolising a source of support.
- Kỵ thần: the line that restrains the dụng thần, symbolising an obstacle.
- Cừu thần: the line that restrains the nguyên thần, symbolising a factor that removes the source of support.
- Thù thần: the line that generates the kỵ thần, symbolising a factor that reinforces the obstacle.
Beyond this, one must also consider the Thế line and the Ứng line. The Thế line is generally regarded as the querent's side, and the Ứng line as the side of the other party, the subject, or the external circumstances. But even the Thế line is not automatically the dụng thần. There are questions where the dụng thần lies in the Ứng line, for example when asking about another person, the subject may lie in the Ứng line rather than the Thế line.
Which line to read for which question?
The table below gathers the ways of choosing the dụng thần by group of matters commonly met in Lục Hào practice. These are widespread conventions, not immutable rules for every school.
| Group of matters asked about | Dụng thần commonly used | Notes |
|---|---|---|
| Wealth, money, income | Thê Tài | Asking about a specific sum of money still uses Thê Tài, not the Thế line |
| Work, position, examinations, litigation | Quan Quỷ | In litigation, Quan Quỷ may be taken as the opposing party |
| Parents, teachers, documents, houses, vehicles | Phụ Mẫu | Documents and contracts are usually assigned to Phụ Mẫu |
| Children, students, medicine, health | Tử Tôn | In illness questions, Tử Tôn is usually taken as the medicine, as the removal of the affliction |
| Siblings, friends, peers or rivals | Huynh Đệ | Also used when asking about sharing or competition |
| The querent themselves | Thế line | The Thế line is not always the dụng thần |
| Spouse, marriage partner | Thê Tài or Quan Quỷ | Depending on gender and on school, see the section below |
| Objects, belongings, specific property | Thê Tài | Material things in general are assigned to Thê Tài |
One easily confused point deserves attention: asking about oneself does not mean always taking the Thế line as the dụng thần. If the question is "will I get the job", then the dụng thần is Quan Quỷ, while the Thế line only shows the position and state of the querent within that situation. The Thế line and the dụng thần are two different concepts, and they are often conflated in short introductory guides.
Which line to take when asking about marriage?
Questions about marriage usually take Thê Tài and Quan Quỷ, but the way these are assigned to men and women is not consistent between schools. Some schools follow the convention that a man takes Thê Tài as his wife, and a woman takes Quan Quỷ as her husband. Other schools interpret by the role within the question rather than by the querent's gender, for example whoever is being asked about is assigned the line corresponding to that person, regardless of male or female.
This difference is not a matter of right or wrong, but of differing convention. A student should choose one school, state clearly which convention they follow, and keep it consistent. Mixing two conventions within a single hexagram will lead to contradictory conclusions.
Which line to take when asking about health?
Questions about health are the group of matters with the most differing ways of choosing the dụng thần. One way takes the Thế line as the sick person, Quan Quỷ as the illness, and Tử Tôn as the medicine and recovery. Another way takes Phụ Mẫu as the body, since Phụ Mẫu generates us, and then interprets by generation and restraint. There is also a way that divides by body part and assigns each part to a line.
Because this is a field directly concerned with health, it must be said clearly: no result of casting a hexagram can replace medical diagnosis and treatment. A hexagram can only be regarded as a way of organising one's own thoughts, not as a basis for deciding whether to go for a check-up, or for stopping medication.
When a hexagram has two lines of the same kind, which one is taken as the dụng thần?
When the dụng thần appears twice in a hexagram, that is, when there are two lines of the same kind such as two Phụ Mẫu lines or two Huynh Đệ lines, then the moving line is taken as the dụng thần. This is the rule, together with examples of divining about parents where the hexagram has two Phụ Mẫu lines, or divining about siblings where the hexagram has two Huynh Đệ lines.
When there is no moving line, or when a clearer distinction is needed between two lines of the same kind, the following order of priority may be considered:
- Give priority to the moving line first, because the moving line is the line undergoing change and directly taking part in the matter.
- If both are moving or both are static, give priority to the line that is strong and flourishing in the month and day, because a flourishing line has stronger expressive power.
Set aside any line falling into Tuần Không (void) or Nguyệt Phá (broken by the month), since it is stated clearly: a line is only truly void when it meets all the conditions, such as being void while also weak, imprisoned, at rest, restrained by the day spirit, restrained by a moving line, hidden and restrained, or static and broken by the month. A line in such a condition can hardly represent the subject under consideration.
An example shows how this is applied: on a Bính Tuất day in the month of Hợi, divining for a friend standing for election, the hexagram Trạch Hỏa Cách changing to Thiên Hỏa Đồng Nhân was obtained. The hexagram had quan quỷ appearing twice, that is, two Quan Quỷ lines, and the interpreter took the activated line as the dụng thần. This line was in harmony with the day spirit, and although it had a touch of voidness, it was moving and transforming into advance, so victory was predicted. This case shows that the moving line is both a criterion for choosing the dụng thần and a criterion for judging fortune and misfortune.
It should be added that the doubling of the dụng thần does not occur only in the Quan Quỷ group. The phenomenon of two lines of the same kind appears frequently when divining about relationships or about factors of a repetitive nature, for instance divining about parents where the hexagram has two Phụ Mẫu lines, or divining about siblings where the hexagram has two Huynh Đệ lines. In such cases, choosing the right one of the two lines is decisive, because the two lines may give two different signals.
How do Du hồn and Quy hồn hexagrams, and the palace of the hexagram, affect the way the dụng thần is read?
Du hồn (Wandering Soul) and Quy hồn (Returning Soul) hexagrams do not change the dụng thần, but they change the tone of the whole hexagram, so the reading of the dụng thần must be placed in that context. Du hồn and Quy hồn originate from the transformations of the Bát Quái (Eight Trigrams): Du hồn is the seventh hexagram of each palace, for example the hexagram Thủy Thiên Nhu in the Khôn palace. Because that transformation implies departure and wandering, when a hexagram turns into Du hồn the information usually revolves around movement, instability, or an outward tendency.
The same source also notes that Du hồn is not an independent hexagram but a special state that appears when a moving line causes the hexagram to change into another hexagram. Du hồn does not directly indicate clear fortune or misfortune as the other lines do; instead it carries the meaning of uncertainty, dispersion, or a wavering spirit, and plays a supporting role in clarifying the nature of the matter or of the person asked about. When Du hồn appears, the usual sign is an inner disturbance, which may manifest as anxiety, unease, loss of direction, or matters belonging to mental health.
For the reading of the dụng thần, this leads to several practical consequences:
- If the dụng thần is flourishing but the hexagram is Du hồn, then the flourishing may speak only of potential and not of stability. The subject may be strong but in a state of movement, hard to grasp.
- If the dụng thần is in the Thế line and the hexagram is Du hồn, then the querent's state may be one of unease, dispersion, wanting to leave, or being outside a familiar sphere of influence.
- If the dụng thần is in the Ứng line and the hexagram is Du hồn, then the other party or the external circumstances are in flux, not standing still.
The palace of the hexagram is also a layer of context. Du hồn is the seventh hexagram of each palace, so knowing which palace the hexagram belongs to tells us from which group of relationships that movement arises. The same Du hồn signal, placed in the Khôn palace, the Càn palace or the Đoài palace, will suggest different areas of life. Even so, it is also reminded: if Du hồn is overused or misunderstood, the reader easily overlooks important details or concludes too early. For that reason it should only be an extra layer of reading, and must not be used to replace the interpretation of the dụng thần by generation, restraint, strength and weakness.
Why are there matters that should not be put to the hexagram?
There are matters that should not be put to the hexagram because the answer cannot be put to any use, or because the way of asking itself already muddies the result. This is a view repeated by many Lục Hào practitioners, and it is also a reasonable point in psychological terms.
The groups of matters commonly advised against asking about:
- Matters already too clear, with no other option left: asking only to confirm what one already knows creates no further information.
- Matters asked to test the hexagram or to test the diviner: the question does not arise from a real need, so there is no real dụng thần to choose.
- Asking the same matter over and over again: each cast is a new hexagram, the hexagrams will differ, and choosing which one to believe becomes arbitrary.
- Asking about matters beyond one's own reach: for example asking about another person's affairs when one has no role in them, or asking about great events beyond any individual's power to affect.
- Asking in place of one's own decision: a hexagram may suggest a direction of thought, but it should not be the thing that takes responsibility on the querent's behalf.
- Asking about things that harm others: this kind of question has no place in any serious tradition.
Technically, the reason lies in the fact that the dụng thần must be tied to a real subject and a real question. When the question is vague or has no specific subject, the interpreter is forced to infer the dụng thần themselves, and the result becomes a product of that inference rather than of the hexagram.
What does choosing the wrong dụng thần lead to?
Choosing the wrong dụng thần leads to the whole chain of interpretation afterwards being skewed, even if the steps of generation and restraint are calculated correctly. This is the most common mistake when first learning Lục Hào.
Three commonly met situations:
- Taking the Thế line as the dụng thần for every question: this leads to overlooking the line that truly represents the subject, for example asking about money while only reading one's own state.
- Taking the strongest line as the dụng thần: a strong line is merely a strong line in the hexagram, not necessarily the line connected to the question.
- Changing the dụng thần midway when the result is not as hoped for: this is a way of self-deception, and destroys the consistency of the whole hexagram.
A simple way to guard against this is to write the question out as one specific sentence before casting, determine the dụng thần for that question, and then keep that dụng thần unchanged throughout the interpretation. If, after interpreting, the original question turns out to have been too vague, that should be noted rather than adjusting the dụng thần to suit one's wishes.
Where do the schools disagree?
Lục Hào schools do not agree on three main points: how to assign the dụng thần for marriage according to gender, how to choose the dụng thần for health, and how far to use the Thế line as a default dụng thần.
In addition, some modern schools have shifted to interpreting by question and context rather than by a fixed table of conventions, holding that the dụng thần must be inferred from the specific situation and cannot be looked up in a table. Other schools still keep the traditional table of conventions for its consistency and ease of verification.
This article follows the widespread presentation: there is a reference table of conventions, but it stresses that conventions are only a starting point and each school may adjust them. The reader should treat the table as a study tool, not as a fixed law.
