Line relationships in the I Ching: correspondence, holding together, riding and carrying

The six lines of a hexagram are not read in isolation. The commentaries describe two kinds of relationship between them: correspondence (應, ying) between lines in the same place of the lower and upper trigram, and neighbour relations between adjacent lines, called holding together (比, bi), riding (乘, cheng) and carrying (承, cheng). Together with correct place and centrality, these are the main tools the Ten Wings and later commentators use to explain why a line text says what it says.

Correspondence: 1 with 4, 2 with 5, 3 with 6

Each line of the lower trigram has a partner in the same position of the upper trigram: the first line with the fourth, the second with the fifth, the third with the top. If the two are of opposite kinds, one yin and one yang, they correspond (有應, "have a response"). If they are the same kind, two yang or two yin, there is no correspondence; the commentaries sometimes call this 敵應, "rival response."

Wang Bi gave the classic definition in his Outline of the Zhouyi: 應者，同志之象也, "correspondence is the image of shared purpose." A corresponding line is the person or force that answers you from a distance: an ally, a superior who trusts you, a partner who meets you halfway.

The most important pair is 2 and 5, the two central lines. When a yin line in the second place answers a yang line in the fifth, or the reverse, you have the classic picture of a capable official and a ruler who trust each other. That is why the Tuan commentary so often praises a hexagram with the phrase 剛中而應, "firm and central, and responded to."

Two hexagrams show the extremes:

• In Xian, Attraction, every pair corresponds. The Tuan speaks of the two energies "stirring and answering each other," and the whole hexagram is about mutual influence.
• In Gen, Keeping Still, no pair corresponds. The Tuan says 上下敵應，不相與也, "above and below are rival responses; they do not go along with one another." Fitting for a hexagram about stillness, where each part rests on its own.

Holding together: adjacent lines that bond

Neighbouring lines of opposite kinds can hold together (比). This is a closer, more immediate bond than correspondence: the one beside you rather than the one who answers from afar. The idea is named after the hexagram that shows it best, Bi, Holding Together, where a single yang line in the fifth place gathers five yin lines around it:

• The second line "holds to him from within": it corresponds with the fifth from the lower trigram.
• The fourth line "holds to him from outside": it has no correspondence (the first line is also yin), so it bonds with its neighbour, the fifth, directly above. Its small Image reads 外比於賢，以從上也, "holding outwardly to the worthy, following the one above."
• The top line "holds together without a head: misfortune." It sits above the ruler, late and outside the circle.

The lesson the commentators draw: when a line has no distant ally, its nearest neighbour matters all the more.

Riding and carrying

The two remaining terms describe the direction of a neighbour relation, and they are usually said of a yin line beside a yang one.

• Riding (乘): a yin line above a yang line rides on it. Soft over firm is felt as an inversion, and the commentaries treat it as a source of difficulty.
• Carrying (承): a yin line below a yang line carries or supports it. Soft under firm is the natural order, and it is usually favourable.

Wang Bi put both in one phrase: 承乘者，逆順之象也, "carrying and riding are images of going against and going with the grain."

The clearest example of riding is the second line of Zhun, Difficulty at the Beginning: "difficulties pile up; horse and wagon part. Not a robber, but a suitor. The maiden is steadfast and does not pledge herself; after ten years she pledges." The small Image explains the difficulty as 乘剛也, "it rides on the firm": the yin second line sits on top of the strong yang first line, which pulls at it, while its true partner is the yang fifth line with which it corresponds. The whole text plays out the tension between the neighbour pressing from below and the distant correspondence it waits for.

Riding at its most extreme is Guai, Breakthrough, where one yin line sits on top of five yang lines. The Tuan names it: 柔乘五剛也, "the yielding rides on five firm lines." The whole hexagram is about removing that one line.

Carrying shows up in lines that stand just below a strong ruler and serve it well. In Guan, Contemplation, the fourth line, yin, right under the yang fifth, "contemplates the light of the kingdom; favourable to be a guest of the king." Close to the ruler, receptive, and useful.

How the relations combine

Real line texts usually involve several of these at once. In Tai, Peace, the yang second line corresponds with the yin fifth, the classic ruler-and-minister pair, and the fifth line's text speaks of a marriage between the ruler's house and a worthy family. In Zhun, the second line's riding and its correspondence pull in opposite directions, and the text is exactly about that tension. When you see a line torn between two pulls, look for this pattern: a neighbour (比, 乘, 承) on one side, a correspondence (應) on the other.

Keep in mind that these relations are interpretive tools, and different commentators weigh them differently. They explain the received text well, but they were applied after the text existed, and not every line text can be derived from them.

Using line relations when you read a cast

When a line moves in your cast, you can ask four quick questions of it:

• Does it correspond? Look at the line three places away. If it is the opposite kind, you have support at a distance; if not, you may be acting alone.
• Who is its neighbour? A neighbour of the opposite kind is a closer, practical bond, for better or worse.
• Is it riding or carrying? A soft line pressing on a strong one beneath it suggests strain or a position you are not equipped to hold; a soft line beneath a strong one suggests service and support.
• Which relation does the text pick up? Often the line text is describing exactly one of these, and seeing which one tells you where the situation's pressure lies.

Then read the line in context: the Judgment, the changing-line rules, and which line rules the hexagram.