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I Ching Birth Hexagram · Hexagram 21 of 64

Hexagram 21, 噬嗑 Shì Kè: jaws closing on what lies between them

噬嗑 Shì Kè is hexagram 21 of the Zhouyi, which joins thunder and lightning in one storm. The figure can be read as an open mouth with something hard lodged between the teeth, and the name means to bite and close the jaws; the tradition reads it as the firm removal of what blocks a union, and its Judgment speaks of law.

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Hexagram 21, 噬嗑 Shì Kè, drawn as six lines numbered from the bottom: whole, broken, broken, whole, broken, whole. The lower, inner trigram is 震 Zhèn, Thunder; the upper, outer trigram is 離 Lí, Fire. 1 2 3 4 5 6 Upper, outer 離 Lí, Fire Lower, inner 震 Zhèn, Thunder 21 噬嗑 Shì Kè Lines numbered from the bottom
The figure of 噬嗑 from the bottom line up: Thunder inside, Fire outside. Three broken lines, three whole.

Facts

Number
21 of 64, in the received order
Character and pinyin
噬嗑 Shì Kè ䷔
Our title
Closing the Jaws
Lines, bottom to top
yang, yin, yin, yang, yin, yang
Lower trigram (inner)
☳ 震 Zhèn, Thunder
Upper trigram (outer)
☲ 離 Lí, Fire
Within (nuclear)
39 蹇 Jiǎn, Obstruction
King Wen pair
22 賁 Bì, Adornment
Legge's name (1882)
Shih Ho
Part of the text
The first part (上經), 1 to 30

Meaning

Look at the figure as a face: a whole line at the bottom and the top for the jaws, broken lines for the open mouth, and one whole line in the fourth place lodged between them like something hard. The name 噬嗑 means to bite and bring the jaws together, and the tradition reads the hexagram as biting down hard on an obstacle so that the two sides can meet. Thunder below and lightning above make one storm, noise and light at once.

The Judgment and the Image take the picture into government. Legge's English speaks of "legal constraints", and the Image says the early kings made their penalties clear and their laws known, as lightning makes things plain. This is the language of a Bronze Age court, and we give it as the text's own. In our reading the hexagram is about dealing decisively with what stands in the way, and about measure: firm enough to bite down, fair enough not to become cruelty. It says nothing about anyone's legal affairs.

The lines

The line texts are the book's most penal, with stocks and old punishments at the bottom and top, which we leave to the text. In between is a sequence about eating: biting into soft flesh, gnawing dried meat and meeting something unpleasant, gnawing meat dried on the bone and finding metal arrows in it. The fifth gnaws dried meat and finds "the yellow gold", in Legge's words, and is told to stay firm and mindful of the danger.

Its pair is 賁, hexagram 22, the same figure upside down; every line flipped gives 井, hexagram 48, the well.

In the birth cast

The time cast arrives at 噬嗑 when the year, month and day leave 3 on eight, which puts 離 fire above, and the same total with the hour added leaves 4, which puts 震 thunder below. Which line moves depends on what the whole total leaves on six, and each line turns the figure into a different hexagram:

  • Line 1 (初九) moving: becomes 35 晉 Jìn, Advance
  • Line 2 (六二) moving: becomes 38 睽 Kuí, Estrangement
  • Line 3 (六三) moving: becomes 30 離 Lí, Brightness
  • Line 4 (九四) moving: becomes 27 頤 Yí, Nourishment
  • Line 5 (六五) moving: becomes 25 无妄 Wú Wàng, Without Pretence
  • Line 6 (上九) moving: becomes 51 震 Zhèn, Shock

Lines 2 to 5 give the hexagram within, 39 蹇 Jiǎn, Obstruction. Everyone born in the same lunar day and double hour has the same cast, so the figure describes a moment, not a person.

Correspondences

Each item with how it stands: “sourced” is in the work cited, “our construction” is EsoTerrier’s own, and “disputed” means the sources disagree.

Trigram virtues (Shuogua, chapter 7)
震 moving, startling below; 離 bright, attached above, in our English sourced
Trigram family places (Shuogua)
eldest son below, middle daughter above sourced
Trigram body and animal images (Shuogua)
feet and dragon below; eyes and pheasant above sourced
Trigram phases (a classical correspondence: the Plum Blossom text's table)
Wood below, Fire above. The Han assignment of 梅花易數, book 1, also used by Jing Fang; not stated as such in the Zhouyi sourced
Inverse and opposite
Upside down: 22 賁 Bì, Adornment; every line flipped: 48 井 Jǐng, The Well sourced
Human Design gate
Gate 21, from 9.5° to 15.125° of the tropical zodiac on Ra Uru Hu's wheel (1987): a modern placing, not the I Ching's sourced
Our English title
Closing the Jaws: EsoTerrier's own, from the sense of 噬嗑 our construction

How the schools read it

The Zhouyi, in Legge's translation (1882)
“Shih Ho indicates successful progress (in the condition of things which it supposes). It will be advantageous to use legal constraints.”
The Image (大象), one of the Wings, in our paraphrase
Thunder and lightning together; the ancient kings framed their penalties with intelligence and promulgated their laws.
The Plum Blossom method (Ming)
A figure reached by numbers: 離 above when the year, month and day leave 3 on eight, 震 below when the same total with the hour leaves 4.
Human Design (Ra Uru Hu, 1987)
Takes the number for its gate 21 and puts it on the zodiac; its own reading, which we do not quote.
EsoTerrier
Thunder and lightning together: jaws closing on what lies between them; what blocks the way is dealt with firmly and fairly, and then the jaws can meet.

Claims about it

  • Gate 21 of Human Design, at 9.5° to 15.125° of the zodiac, is where the I Ching itself places hexagram 21.

    false

    What the record shows: The wheel is Shao Yong's circle rotated by Ra Uru Hu in 1987 to 1989 so that hexagram 41 starts at 2° Aquarius. No Chinese source we found puts the hexagrams on degrees of the zodiac.

  • Being born under 噬嗑 Shì Kè fixes a person's character.

    unverified

    What the record shows: A modern reading with no source in the tradition. The Zhouyi has no birth hexagram; the cast reads a figure, not a person, and everyone born in the same lunar day and double hour shares it.

Elsewhere on EsoTerrier

Sources

Primary texts (6)
  1. James Legge (trans.), The Yî King, Sacred Books of the East XVI. Oxford: Clarendon Press, 1882. Public domain; quoted briefly and credited. en.wikisource.org/wiki/Sacred_Books_of_the_East/Volume_16
  2. 梅花易數 (Meihua yishu, the Plum Blossom method), attributed to Shao Yong, book 1: the time rule, the trigram numbers and phases, and the casts of the plum blossom and the peonies. zh.wikisource.org/wiki/梅花易數/卷一
  3. 周易 (Zhouyi), the received Chinese text of the hexagram and line statements with the Ten Wings. ctext.org/book-of-changes
  4. The same, the 1882 Oxford edition scanned (archive.org), for hexagrams 33 to 64 and the appendices. archive.org/details/sacredbooksofchi16conf
  5. The Unicode Standard, Yijing Hexagram Symbols, U+4DC0 to U+4DFF. unicode.org/charts/PDF/U4DC0.pdf
  6. 京氏易傳 (Jingshi yizhuan), attributed to Jing Fang, three books. zh.wikisource.org/wiki/京氏易傳
Studies and other sources (3)
  1. "King Wen sequence", Wikipedia. en.wikipedia.org/wiki/King_Wen_sequence
  2. Jovian Archive, "Gates and hexagrams in Human Design" (cited for the wheel's origin only). jovianarchive.com/pages/gates-and-hexagrams-in-human-design
  3. "Hexagram (I Ching)", Wikipedia. en.wikipedia.org/wiki/Hexagram_(I_Ching)
Our own research (5)
  1. EsoTerrier, I Ching research, 10 to 14 October 2026: the method, the validation (61 births), the variants and the lists.
  2. EsoTerrier calculation engine, the I Ching service and its reference tables (titles, glosses and readings our own).
  3. EsoTerrier, Gene Keys research, 9 October 2026: the legal and trade-mark report, on which hexagram names are free to use.
  4. EsoTerrier, Human Design research, 9 October 2026: the wheel, gate 41 at 2° Aquarius, 5.625° per gate.
  5. EsoTerrier, engine audit of 14 October 2026: the reworded titles, readings and trigram qualities, with the passages each rests on.

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By EsoTerrier. Written with AI assistance from our research and checked against its sources; last revised 19 October 2026. How we write these pages.

First published ; last revised . Corrections: support@esoterrier.com.