Why does the same hexagram cast this month differ next month?
Same hexagram, same question, but cast in the Tiger month and then again in the Monkey month, readings usually diverge, sometimes sharply. The reason lies not in the hexagram but in two quantities tied to the moment of casting: the month leader (nguyệt kiến) and the day spirit (nhật thần). The hexagram is only a fixed frame of six lines with their five phases, six relations, and self and other positions; the month leader and day spirit are two outside forces poured into that frame, strengthening one line and weakening another. Changing the casting month changes the month leader, changing the casting day changes the day spirit, so each line's weight shifts.
Zeng Shan Bu Yi by Elder Ye He devotes two separate chapters to the Month Leader and the Day Spirit, placed right after the chapter on the four seasons' flourishing and resting, showing the author treats these as the two main axes to grasp before touching fortune. The Qi Men Zhi Gui, in its section on monthly qi, also records the naming: the first lunar month takes the Tiger as month leader, Tiger belongs to Wood so Wood flourishes, Rabbit is next, Fire is in the supporting state, and the remaining phases fall into resting and imprisoned without qi. This assignment repeats across twelve months to form the flourishing, supporting, resting, and imprisoned table that all Liu Yao schools use, though some name it slightly differently.
How does the month leader measure a line's strength by month?
The month leader is the earthly branch of the lunar month at the time of casting. It acts like the grader for the whole month: a line sharing the month leader's phase is called flourishing, a line generated by the month leader is in the supporting state, a line that generates the month leader is resting, a line that controls the month leader is imprisoned, and a line controlled by the month leader is dead. The four levels flourishing, supporting, resting, and imprisoned are a coarse scale, and dead is the weakest. A line currently resting or imprisoned that meets a generating month leader or is helped by another moving line can still recover, like a person of ordinary ability promoted from outside.
The month leader also has authority to intervene in relations between lines. When a moving line controls a static line, the month leader can subdue that moving line, reducing its effect. When a transformed line controls a moving line, the month leader can also subdue the transformed line. When the useful spirit is hidden under a covering spirit, the month leader can control the covering spirit while generating the useful spirit, clearing the way for the hidden line to emerge. In other words, the month leader not only scores each line but also arranges the play among lines.
One easily overlooked point: the month leader acts on the whole hexagram throughout that month, so the same hexagram cast at the start and end of a month can still differ in which line the month leader lifts and which it presses down, if between the two castings a line has activated or a new transformed line has appeared.
How does the day spirit differ from the month leader?
The day spirit is the earthly branch of the day of casting. If the month leader is the climate of the whole month, the day spirit is the shove of that single day. The day spirit has four main types of effect on a line: generate, control, clash, combine. Generate pours in force, control erodes, clash flips a line up or breaks it depending on state, combine ties a line down or pulls it up depending on direction of reading.
Zeng Shan Bu Yi places the Day Spirit right after the Month Leader, and in its discussion of movement and stillness, generation and control, clash and combination, the author stresses that a flourishing line generated by the day spirit is like weaving flowers on brocade, while a weak line controlled by the day spirit is like frost on snow. This phrasing shows the day spirit is not neutral: it amplifies a line's existing state rather than creating a new state from nothing.
The day spirit also determines which line counts as hidden movement and which counts as day breaker. The same line clashed by the day, if flourishing, is called hidden movement; if resting or imprisoned without qi, it is called day breaker. This is where beginners often confuse the two, since both cases mention clash.
Table of void in the decade for the six Jia decades
Void in the decade, also called emptiness, arises from the mismatch between ten heavenly stems and twelve earthly branches. One Jia decade spans ten days, pairing ten stems with ten of the twelve branches, so two branches are always left unpaired. Those two are the void of that decade. The Liu Ren, in its introductory volume, explains the same arithmetic: the least common multiple of 10 and 12 is 60, so ten stems pair with twelve branches into six Jia decades, each leaving two unused branches called void. Void has the power to empty, meaning it blurs a line's force during that decade.
| Jia decade | Days in the decade (example) | Two void branches |
|---|---|---|
| Jia Zi | Jia Zi, Yi Chou, Bing Yin, Ding Mao, Wu Chen, Ji Si, Geng Wu, Xin Wei, Ren Shen, Gui You | Xu, Hai |
| Jia Xu | Jia Xu, Yi Hai, Bing Zi, Ding Chou, Wu Yin, Ji Mao, Geng Chen, Xin Si, Ren Wu, Gui Wei | Shen, You |
| Jia Shen | Jia Shen, Yi You, Bing Xu, Ding Hai, Wu Zi, Ji Chou, Geng Yin, Xin Mao, Ren Chen, Gui Si | Wu, Wei |
| Jia Wu | Jia Wu, Yi Wei, Bing Shen, Ding You, Wu Xu, Ji Hai, Geng Zi, Xin Chou, Ren Yin, Gui Mao | Chen, Si |
| Jia Chen | Jia Chen, Yi Si, Bing Wu, Ding Wei, Wu Shen, Ji You, Geng Xu, Xin Hai, Ren Zi, Gui Chou | Yin, Mao |
| Jia Yin | Jia Yin, Yi Mao, Bing Chen, Ding Si, Wu Wu, Ji Wei, Geng Shen, Xin You, Ren Xu, Gui Hai | Zi, Chou |
How to look up: take the stem and branch of the casting day, find which Jia decade it belongs to, then read the corresponding two void branches. For example, on a Jia Zi day, Xu and Hai are void; any line carrying branch Xu or Hai in a hexagram cast that day is considered to be in void. The Liu Ren adds that void is not always bad: a malefic spirit meeting void loses force, but a benefic spirit meeting void also loses its blessing, sometimes entirely.
Table of month breaker by month
Month breaker is the state of a line clashed by the month leader. In the phrasing recorded in Liu Yao texts, any line clashed by the month is called broken. The difference from day breaker lies here: a flourishing line clashed by the day is called hidden movement, while a resting or imprisoned line without qi clashed by the day is called day breaker; month breaker is heavier, usually read as decline, hard to turn around within that month.
| Month (month leader branch) | Branch clashed, that is, in month breaker |
|---|---|
| Yin | Shen |
| Mao | You |
| Chen | Xu |
| Si | Hai |
| Wu | Zi |
| Wei | Chou |
| Shen | Yin |
| You | Mao |
| Xu | Chen |
| Hai | Si |
| Zi | Wu |
| Chou | Wei |
How to use: when casting in the Tiger month, any line carrying the Monkey branch is called in month breaker. This table is built directly from the six-clash relation among earthly branches, so it can be derived from the calculation core without typing each row by hand.
What do the three utility states printed by Liu Yao software mean: void, month breaker, hidden movement?
These three labels are not three different kinds of line, but three states layered onto an existing line. A line can be both in void and in month breaker, or be in hidden movement yet fall into void.
Void: the line sits in the two unpaired branches of the Jia decade containing the casting day. The effect is that the line loses force temporarily during that decade. Liu Yao texts record the phrase "flourishing meets void, past the decade still useful," meaning a flourishing line meeting void can still be used once the decade passes. This case is called "not truly void," meaning the void does not fully cancel the line's force.
Month breaker: the line is clashed by the month leader. The effect is that the line declines for the month, read as losing the chance to turn the outcome around. But month breaker is not a death sentence: if a broken line meets a day spirit sharing its branch, or the day spirit combines it up, or a moving line generates and supports it, it can still manifest positively, depending on whether the timing is near or far. If month breaker also meets void, force drops further. If the month leader and day spirit share a phase that controls and harms the broken line, it is called "attained breaking," and only then does the malefic nature show most clearly.
Hidden movement: a line clashed by the day spirit yet still retaining qi, or a resting imprisoned line generated by a moving line, or a flourishing line meeting day clash. The trait of hidden movement is that its force is not lasting but in the short term is as strong as an openly moving line. So hidden movement is usually used for short-term matters: one meeting, one quick decision, one event of a few days. When a hidden-movement line is not confirmed in reality, it shifts to an illusory state, loses the ability to generate and support, returns to day breaker, and may let the outcome follow the openly moving line or other lines without its help.
Answering directly the "is the useful spirit strong or weak" line that software prints
When Liu Yao software prints a line like "useful spirit flourishing" or "useful spirit declining," it is merging four layers of information. The first layer is the flourishing, supporting, resting, imprisoned state by month leader: useful spirit sharing the month leader's phase is flourishing, generated by the month leader is supporting, generating the month leader is resting, controlling the month leader is imprisoned, controlled by the month leader is dead. The second layer is the day spirit's effect: generate, control, clash, combine. The third layer is the labels void, month breaker, hidden movement, day breaker layered onto the line. The fourth layer is the relation to moving lines and transformed lines: a moving line generating the useful spirit raises it, a moving line controlling the useful spirit lowers it, a transformed line generating the moving line raises it, a transformed line controlling the moving line lowers it.
A useful spirit flourishing, generated by the day spirit, not in void, not in month breaker, and supported by a generating moving line, is printed by software as useful spirit flourishing. A useful spirit resting or imprisoned, controlled by the day spirit, and in month breaker, is printed as useful spirit declining. Mixed cases, for example month controls but day generates, or day controls but month generates, are usually read as even, and one must check moving lines to decide. Zeng Shan Bu Yi, in its discussion of month leader and day spirit, follows this direction too: the month leader and day spirit are stronger than moving lines, but when the two sides contend, the moving line is the tie-breaking vote.
Where the schools disagree
The following four points are where Liu Yao books and schools often differ. This article does not pick one side as standard, only records the readings currently in circulation.
On "clash void then real": some schools hold that a line in void clashed by the day spirit or a moving line has its void broken and becomes useful again, called "clash void then real." Other schools maintain that a line in void stays void until the decade ends, unless combined or filled.
On true void and false void: some distinguish a flourishing line in void as false void, meaning temporarily void and usable after the decade; a resting imprisoned line in void as true void, meaning truly lost force. This distinction is not used by every book; some say void is void, with no true or false split.
On whether month breaker ends when the month passes: some texts hold that month breaker is effective only during that month and ends after, unless the line is further controlled or harmed by the day spirit. Others hold that month breaker leaves a residue, especially when the line is not generated and supported again, so the next month must also be examined.
On whether the day spirit or month leader weighs more: most texts place the month leader heavier because it covers the whole month, while the day spirit is strong only for the day. But some readings hold that the day spirit is what is happening right now, so for questions about the next few days the day spirit must be placed first. Zeng Shan Bu Yi, in its discussion of the three transmissions, says when the month controls but the day generates, or the day controls but the month generates, they are considered even, and moving lines must be checked. This is where the book accepts both directions rather than settling on one.
Same void arithmetic, but Ba Zi and Zi Wei read it differently
The same void arithmetic is used differently by three disciplines. In Ba Zi, void is determined by the Jia decade of the day stem or year stem of birth, then checked against the earthly branches of the year, month, and hour pillars to find where void is offended. Ba Zi texts record the lookup: Jia Zi void at Xu and Hai, Jia Xu void at Shen and You, Jia Shen void at Wu and Wei, Jia Wu void at Chen and Si, Jia Chen void at Yin and Mao, Jia Yin void at Zi and Chou, and some also mention mutual void exchange between year and day, or day and hour. In Zi Wei, the void arithmetic yields the Void Star, and the Void Star is read as a factor that blurs a palace or slows the influence of stars in that palace, rather than meaning temporary loss of force as in Liu Yao. The three disciplines share one counting method, but the meanings assigned to the result differ, so one should not apply one discipline's reading directly to another.
Places where readings easily go wrong
A common error is seeing a combination and rejoicing, thinking combination resolves control. In practice, control usually happens first, then combination reconciles the two sides, so the matter still suffers loss before stabilizing. Another error is reading void and month breaker as two labels of the same kind, when void is effective only during the decade and month breaker only during the month, two different time frames. A third error is reading hidden movement like an openly moving line, when hidden movement's force is short and not lasting, suited only to short-term matters.
One point to remember when reading tables yourself: the void and month breaker tables in this article are built from stem-branch and six-clash relations, not hand-copied data, so they can be verified by checking against the stem-branch calendar of the casting day and month. If a table lookup differs from what software prints, check which time zone the software uses for the day stem and branch, since this is where a one-day offset often occurs, dragging the void decade with it.
Conclusion: how to read it
The month leader and day spirit do not change the hexagram, they change each line's weight within it. So the same hexagram cast at two different times can give two different results without contradiction. Void, month breaker, and hidden movement are three labels layered onto an existing line, each with its own time frame: void by decade, month breaker by month, hidden movement by day and usually strong only short term. When software prints useful spirit flourishing or declining, that is a merged result of four layers of information, not an absolute verdict. Schools still differ on clash void then real, true void and false void, whether month breaker ends when the month passes, and whether the day spirit or month leader weighs more, so a fortune conclusion should be read only as a tendency for reference, not used to assert certainty about a person's finances, health, or fate.
FAQ
1. Why does the same hexagram cast this month differ next month?
Because the month leader and day spirit at the time of casting set each line's strength. Changing the month changes the month leader; changing the day changes the day spirit. The hexagram frame stays the same, but the weight of each line shifts, so readings diverge.
2. How do void, month breaker, and hidden movement differ?
Void is a line sitting in the two unpaired branches of the casting day's Jia decade, losing force temporarily during that decade. Month breaker is a line clashed by the month leader, declining for that month. Hidden movement is a line clashed by the day spirit yet still retaining qi, acting in the background with short-lived but strong effect.
3. Does month breaker end when the month passes, and does the day spirit or month leader weigh more?
Some texts hold month breaker is effective only during that month and ends after, unless the line is further harmed by the day spirit; others hold it leaves a residue and the next month must also be examined. Most texts place the month leader heavier since it covers the whole month, but some readings put the day spirit first for questions about the next few days, and Zeng Shan Bu Yi treats month control with day generation, or day control with month generation, as even, requiring moving lines to decide.
