Tai Yi is one of those names that carries several meanings at once: a star, a deity, an ancient philosophical idea, and the title of a divination method. This piece sets out which layer is in play where, and why the astronomical background behind the name still shapes the way the method is read.
Tai Yi Shen Shu stands beside Qi Men Dun Jia and Da Liu Ren as one of the Three Styles, yet it circulates far less widely than the other two. Thin documentation, differing conventions and a large framework push the entry cost up; a useful first step is to see what each of the Three Styles is for.
A Da Liu Ren chart is built from elements such as Tai Sui, the divination hour, the monthly general and the void branches, and its core is the Four Lessons and the Three Transmissions. The Four Lessons are derived layer by layer from the upper and lower spirits, while the Three Transmissions fall into nine types according to the controlling and punishing relations between those lessons, known as the Nine Gates; read the structure first and the judgment afterwards.
In Da Liu Ren, which belongs to the same Three Styles, the first of the Three Transmissions is also called the active use, or the useful element, and in Qi Men the same step comes first. Choose the wrong useful element and every later layer fails to line up; the ways of choosing it differ between systems, so it is worth asking which set the other person is using.
A Qi Men Dun Jia chart sits on the nine-palace square of the Luo Shu, and three layers are stacked over it: the nine stars of the heaven plate, the eight spirits of the spirit plate, and the fixed trigram directions of the earth plate. When reading, learn the squares (the nine-palace grid) first, then the layers; jumbling the three together is the most common place beginners stumble.
