Later Heaven bagua: the King Wen arrangement, directions and seasons

The Later Heaven arrangement (後天八卦, houtian bagua) sets the eight trigrams around the compass in the order of the year: Zhen (Thunder) in the east for spring, Li (Fire) in the south for summer, Dui (Lake) in the west for autumn, Kan (Water) in the north for winter, with the other four in the corners. It comes from a passage in the Shuogua, is traditionally attributed to King Wen, and is the arrangement that feng shui, the nine palaces and most calendar-based systems actually use.

The source: one passage of the Shuogua

The Shuogua (說卦), the trigram commentary among the Ten Wings, describes the year as a journey of 帝, "the Lord" or the creative power, through the eight trigrams:

帝出乎震，齊乎巽，相見乎離，致役乎坤，說言乎兌，戰乎乾，勞乎坎，成言乎艮。

"The Lord comes forth in Zhen, brings things to completeness in Xun, lets them see one another in Li, sets them to work in Kun, gives them joy in Dui, battles in Qian, toils in Kan, and brings them to completion in Gen." The text then names the directions: Zhen is the east, Xun the south-east, Li is the trigram of the south, Dui is mid-autumn, Qian the north-west, Kan the north, Gen the north-east — the place where things both end and begin. Kun's direction is not named outright, but its position in the sequence puts it in the south-west.

The Shuogua passage is ancient; the habit of calling the diagram "King Wen's" goes back to the Song, to Shao Yong (邵雍), who contrasted it with his Early Heaven circle. Read the Shuogua passage in context in the Shuogua guide.

The arrangement, direction by direction

Chinese diagrams put south at the top. Going around in the order of the year:

• Zhen ☳ — east — mid-spring — wood. Thunder, the first stirring; things come forth.
• Xun ☴ — south-east — late spring to early summer — wood. Wind, growth spreading out.
• Li ☲ — south — midsummer — fire. Light and full visibility; things "see one another."
• Kun ☷ — south-west — late summer — earth. The field at work, ripening.
• Dui ☱ — west — mid-autumn — metal. Harvest and joy.
• Qian ☰ — north-west — late autumn to early winter — metal. Yin and yang contend as the year turns cold.
• Kan ☵ — north — midwinter — water. Toil, rest and gathering in.
• Gen ☶ — north-east — late winter to early spring — earth. Stillness, where one year ends and the next begins.

The trigram pages in the trigram library give each one's images in full; the eight trigrams guide is the place to start if the names are new.

The seasons and the elements

Follow the elements round the circle and something tidy appears: wood (Zhen, Xun) gives way to fire (Li), fire to earth (Kun), earth to metal (Dui, Qian), metal to water (Kan), water to earth (Gen), and earth back to wood. That is the generating cycle of the five elements, with earth placed at the two seasonal hinges. The Early Heaven circle shows how yin and yang are composed; the Later Heaven circle shows how they move through time.

The calendar picks up the same structure. In the Han "hexagram-and-qi" (卦氣) system associated with Meng Xi, the four cardinal trigrams Kan, Zhen, Li and Dui each govern a season, and their twenty-four lines match the twenty-four solar terms. The eight trigrams also line up with the eight seasonal nodes: Gen with the Start of Spring, Zhen with the spring equinox, Li with the summer solstice, Kan with the winter solstice, and so on round the year.

The family and the nine palaces

The Shuogua also makes the trigrams a family: Qian the father, Kun the mother, Zhen, Kan and Gen the eldest, middle and youngest sons, Xun, Li and Dui the eldest, middle and youngest daughters. In Later Heaven the parents stand in the north-west and south-west, the sons gather on the north and east side, and the daughters on the south and west.

Put a ninth cell in the centre and the arrangement becomes the nine palaces (九宮), numbered by the Luo Shu magic square: Kan 1, Kun 2, Zhen 3, Xun 4, centre 5, Qian 6, Dui 7, Gen 8, Li 9. Every row, column and diagonal adds to fifteen. The link between the trigrams and the nine palaces is already found in Han-dynasty writings and became standard later.

Why feng shui and the calendar use Later Heaven

Because it is a map of process — of time and place — Later Heaven is the arrangement used wherever orientation matters:

• Feng shui. Eight Mansions assigns houses and people to the eight Later Heaven trigrams by direction; Flying Star feng shui moves the Luo Shu numbers through the nine palaces year by year.
• Qimen Dunjia and other nine-palace systems lay their charts out on the same grid.
• Plum Blossom divination reads an omen's direction with Later Heaven, even though it converts numbers into trigrams with the Early Heaven sequence; see Plum Blossom numerology.

The usual summary is 先天為體，後天為用: Early Heaven is the underlying structure, Later Heaven the working map. When you see a bagua diagram, look for Qian. At the top, it is Early Heaven; in the north-west corner, Later Heaven.

How to remember it

Three ways work well, and you only need one:

• Learn the Shuogua sentence. 帝出乎震 … 成言乎艮 lists the trigrams in order; start in the east and walk round the year.
• Learn the Luo Shu rhyme: 戴九履一，左三右七，二四為肩，六八為足 — "nine on the head, one on the feet, three on the left, seven on the right, two and four the shoulders, six and eight the feet." With south at the top, that puts Li 9 at the top, Kan 1 at the bottom, Zhen 3 on the left (east), Dui 7 on the right (west), Kun 2 and Xun 4 at the shoulders, Qian 6 and Gen 8 at the feet.
• Anchor the four seasons. Fire is summer in the south, Water is winter in the north, Thunder wakes spring in the east, the Lake of harvest is autumn in the west. The corners fill themselves in: father Heaven and mother Earth in the two western corners, Wind and Mountain in the two eastern ones.

Using Later Heaven when you read a cast

The I Ching texts were written without any compass diagram, and you can read a cast well without one. Later Heaven helps when your question has a when or a where in it. If a cast is dominated by Zhen, the Thunder trigram, the tradition associates it with beginnings, the east and spring; if by Kan, with winter, the north and a time of effort. Treat these as images that may clarify the text, not as a timetable. Timing in the I Ching is always a matter of reading the situation; see timing questions for a fuller discussion. Then return to the Judgment and the changing lines: they remain the answer.