Also known as: Yin Wood · Vine Wood
Yi is yin wood — vines, grasses, garden flowers. Where Jia is the upright trunk, Yi is the climbing creeper that wraps around what supports it. As a Day Master it grants gentle persistence, social grace, and a flexibility that bends without breaking. Yi people often advance not by confrontation but by attaching to allies and quietly outlasting opposition.
Yi welcomes warm sun (丙) to bloom and fears cold metal (庚 / 辛) cutting it down. The classical combination 乙庚合化金 marries soft yin wood to yang metal — refining sharpness through tenderness, common in charts of artisans and diplomats.
The line from Di Tian Sui most often quoted about Yi is the image of a vine tied to a Jia trunk: once the creeper has the tree, neither spring nor autumn threatens it. Applied to a chart, this means a Yi day master with Jia showing in the stems, or with roots in Yin or Mao below, has a frame to hold and does not sway loose. The same passage warns that waterlogged ground troubles Yi even during a fire period, since sodden wood will not take flame. What Yi attaches to matters more than the attaching: if the Jia is itself rootless, the support is unreliable.
Reading Yi starts with roots. Its salary position is Mao (卯), and it commonly roots in Mao, Wei, Chen, and Hai; if Jia also appears in the stems, the vine-on-trunk reading applies and is treated differently from plain competitor-stem rivalry. Season comes next, and it fills in the general preference for Bing fire and wariness of metal already noted above. Spring Yi, already strong, wants Bing fire to express and Gui water to moisten; summer Yi fears dryness and takes water first; autumn Yi, cut by metal, usually wants Ding fire; winter Yi needs Bing to thaw before anything else is discussed. In the Ten Gods scheme Yi meets Geng as Direct Officer and Xin as Seven Killings. Both are metal controlling wood, yet the Officer implies regulation and the Killings pressure, distinguished classically as pruning against felling.
The sharpest disagreement around Yi concerns how yin stems rise and fall. One line applies the twelve growth stages with yin stems running backwards, so Yi is born at Wu (午) and dies at Hai (亥). Another holds that yin and yang stems flourish and fade together, and treats the reversed sequence with open reservation. That second position is often filed wholesale under Di Tian Sui, which needs one qualification: the base text says of this question only that the forward-and-reverse rule should not be applied rigidly, and it does not deny the reversed cycle. The systematic case against a reversed cycle for yin stems belongs to the Qing commentator Ren Tieqiao, in his annotated Di Tian Sui Chan Wei. Under the two conventions the same Yi can be judged strong or weak. Where the blade falls for yin stems, or whether they have one at all, is unsettled in the same way.
Yi (乙 yǐ) did not begin as a flower either. Han glosses on the stem names describe it as the crooked push of a sprout forcing its way up through packed soil, and the Shuowen jiezi explains the graph through the same image of spring growth bending as it emerges. In the Jing Fang system of matching hexagrams to stems, Yi belongs to Kun, pure yin, the receptive that carries what is set upon it. Read together, the softness of Yi was never weakness; it was detour. Several assumptions fall away with that. Yi does not mean weak, and it certainly does not mean female, since the yin and yang of the stems classify mode and carry no gender; men with yin-heavy charts are entirely ordinary. The Yi-Geng bond does not imply that someone loses their own direction or must submit, since the bond is a pull between two stems and transformation into metal carries separate conditions. And the assumption that Yi simply carries less weight than Jia misses that resilience is itself a form of strength.
The stem of the day pillar stands for the person, so a chart whose day stem is Yi (乙 yǐ) is called a Yi wood chart — yin wood, pictured traditionally as vines and flowering plants and associated with flexibility and indirect persistence. Jia and Yi differ in mode, and neither outranks the other. How strong a Yi actually is depends on the birth month, on whether Mao, Wei, Chen, or Hai appear below as roots, and on what around it supports or drains it. A Yi born in the Mao month with Wei and Hai below is far stronger than a Jia standing alone in the stems over a chart full of Shen and You.
It is the Di Tian Sui image for Yi wood: a creeper that has found a tree is safe whichever season comes. In a chart it describes a Yi day master with Jia in the stems, or with wood roots in the branches below — the soft wood now has a frame and is not simply blown about. The traditional emphasis falls not on dependence but on the quality of what is leaned on: if the Jia itself is rootless, the support is unreliable.
It depends. Geng is Direct Officer to a Yi day master, so metal controlling wood carries a sense of regulation, and the two also form one of the classical stem pairs, which adds a pull between them. The tradition checks two things: whether the wood has enough root to bear that constraint, and whether fire is present to restrain the metal or water to mediate. Rooted and mediated, it is usually read as workable; rootless and unmediated, as strain.
Winter months are water-strong and cold, and sodden wood is traditionally said to have trouble expressing itself. The usual first step is to look for the seasonal corrective: whether Bing fire shows in the stems to warm the chart, whether any wood roots sit below, and whether water is so abundant that it floats the wood instead of feeding it. With usable fire and water kept in proportion, winter Yi reads well; without fire the reading turns to stagnation.