What Does Tai Yin Govern?

The Tai Yin chapter opens by discussing Tai Yin through the phases of the moon: at the first quarter the moon is waxing and its strength growing; at the last quarter it is waning, 「減威」. This line of thought is unique to the Quan Shu, and it pairs with the Tai Yang chapter's use of the hours of the day: Tai Yang is read by time of day, Tai Yin by waxing and waning. Its three roles, transformed qi of wealth, master of the Property Palace and partner of the sun, are all used later.

Worth knowing: the brightness table used in Xingge's chart-building sets Tai Yin's brightness only by the palace it is in, and it does not change with whether the birthday falls early, mid or late in the lunar month. So the Miao or Xian seen on the chart is only one of the Quan Shu's two standards. To judge by this passage's first and last quarters, one can look separately at the lunar birth date: around the 8th is the first quarter, around the 23rd the last quarter, and on the full moon (the 15th) it is fullest and brightest. Later schools also judge the sun and moon by day birth and night birth, a view the Quan Shu mentions too in the Parents Palace chapter.

「日在卯，月在酉，俱為旺地」 means the sun and moon each sit in a position with light. As the note explains, the two never occur together on the same chart, so the line should be read as two separate conditions: Tai Yang in Mao is good, and Tai Yin in You is good too. Tai Yin is Wang in You, and in Master Xiyi's scheme in segment 4, You is 'the gate of the western mountains', the dusk position from which the moon's night-time palaces begin.

「仍以不逢巨門為佳」 has a chart fact behind it: under the placement rules, Tai Yin and Ju Men always have exactly one palace between them, so they never share a palace or meet in the San Fang Si Zheng, and this taboo can only arise in luck periods or with moving stars. 「身若居之，則有隨娘繼拜，或離祖過房」 is a six-relations verdict for Tai Yin in the Body Palace: Tai Yin is the mother star, and the Body Palace is where one ends up in later life, so the ancients read it as going with one's mother, changing surname or being adopted. Today it fits better to read it as a deep tie to the mother's side, and possibly a family that was reorganised while growing up.

The condition for 「惡殺交沖，必作傷殘之論」 is Tai Yin in the Body or Life Palace with malefic stars clashing at it from the opposite palace and the San Fang. Tai Yin is a soft star and bears clashes worst. 「除非僧道，反獲禎祥」 is the Quan Shu's standard remedy, which today can be read as stepping away from worldly competition and taking a religious or contemplative path.

「與文曲同居身命，定是九流術士」 is well worth comparing: the Tai Wei Fu says 「太陰會文曲於妻宮，蟾宮折桂，文章全盛」 (see Tai Wei Fu), so the same pair of stars in the Spouse Palace is a sign of examination success, yet in the Body or Life Palace it makes a practitioner of the nine schools. This shows how heavily the Quan Shu's verdicts depend on the palace. The old nine schools included medicine, divination, astrology and physiognomy; today they correspond to occupations that live by specialist skills, such as healthcare, fortune-telling, counselling and the arts, and need not be read as a slight.

Master Xiyi cuts Tai Yin's fallen and strong places cleanly in two: Mao, Chen, Si, Wu and Wei are fallen; You, Xu, Hai, Zi and Chou hold their ground. The brightness table Xingge uses broadly agrees: Xian in Mao, Chen and Si, Bu in Wu and Wei, Wang in You and Xu, and Miao in Hai, Zi and Chou; Yin, which Master Xiyi does not mention, is Wang, and Shen is Li. The brightness in the small text that readers see on the chart follows this standard.

The four taboos in the second half have something in common: under the placement rules, Ju Men, Lian Zhen and Qi Sha never fall in Tai Yin's San Fang Si Zheng, while Qing Yang and Tuo Luo can share its palace. So the only part of this passage that can actually be checked on a natal chart is Qing Yang or Tuo Luo in the same degree. The others speak of nature: Ju Men's darkness blocks the moonlight, and Lian Zhen's prisoner and Qi Sha's killing force are too hard for the gentle Tai Yin. When a luck-period chart is laid over the natal one, these combinations can appear.

This passage breaks down Tai Yin's effects in each palace once more. Most important is the general rule at the start: 「有輝為福，失陷必凶」. Tai Yin's fortune is decided almost entirely by brightness, more clearly than for any other main star. Men and women both take Tai Yin as the mother star, and men also as the wife star, so Tai Yin's brightness needs special attention in the Parents and Spouse Palaces.

The three combinations in the Health Palace all concern the eyes and illness: Tuo Luo and Ju Men, eye disease; Huo Xing and Ling Xing, disaster; Tan Lang and Qi Sha, damaged eyes. Tai Yin governs the eyes (together with Tai Yang), a fixed correspondence in the Quan Shu. In the Parents Palace, 「陷地失輝，遇流年白虎太歲，主母有災」 is a method of stacking natal and annual charts: a weak natal Tai Yin is the base, and the annual Bai Hu and Tai Sui arriving is the trigger; see the approach to the Annual Luck.

The closing line reminds us again that Tai Yin, 「雖純和」, is unlucky when it lacks light and is under restraint. Bai Hu, Sang Men and Diao Ke are all among the twelve annual spirits before Tai Sui, governing injury, funerals and mourning. The point here is that when the year brings these spirits to overlap with Tai Yin, one should watch the wife's health and safety, because Tai Yin is the wife star in a man's chart.

Today such a verdict can be read as: that year, the health and mood of older women in the family or of one's partner need more care. Whether it comes true still depends on the structure of the natal Spouse and Parents Palaces; the spirit stars alone are not enough to judge.