Upper trigram
☲
Fire · Li
Clarity and attachment.
FamilyMiddle daughter
ElementFire
Hexagram 21 of 64
☲☳ Biting Through
Hexagram 21 of the 64, Biting Through, is fire above, thunder below — read as decisive action against an obstruction. Its six lines are 001101, counted from the bottom up, where a broken line is yielding and a solid one firm.
Lower trigram
☳
Thunder · Zhen
Arousal and shock.
FamilyEldest son
ElementWood
From the Book of Changes itself
The Judgement and the Image
The Judgement
Biting through has success. It is favourable to let justice be administered.
The Image
Thunder and lightning. The ancient kings made firm the laws through clearly defined penalties.
These two texts are the hexagram. Everything else — the trigram analysis, the line positions, the modern keyword — is commentary built on top of them. The Judgement states the situation and its outlook; the Image draws the practical conclusion, and by convention begins with what the trigrams show in nature.
Rendered in plain English from the canonical text rather than copied from any one translation. If you want a specific scholarly version, Wilhelm-Baynes and Lynn are the two usually recommended.
The six lines
Read from the bottom up. This figure runs yin yin yang yang yin yang — what each position means.
| Line | This hexagram | What the position means |
|---|---|---|
| 6 | ▬▬▬▬▬ yang | the situation past its peak — completion, or overreach |
| 5 | ▬▬ ▬▬ yin | the ruling position, usually the most favourable in the hexagram |
| 4 | ▬▬▬▬▬ yang | entering the outer sphere — proximity to authority, exposure |
| 3 | ▬▬▬▬▬ yang | the transition point, and the most dangerous position in the figure |
| 2 | ▬▬ ▬▬ yin | the inner sphere — home, private life, what you are among your own |
| 1 | ▬▬ ▬▬ yin | the beginning of the situation, still hidden and barely formed |
What the two trigrams do to each other
Inner and outer
The lower trigram is the inner situation — Thunder, arousal and shock. This is what is happening in you, or in the private side of the matter.
The upper trigram is the outer situation — Fire, clarity and attachment. This is the world the inner position meets.
The five-element relation
Wood below generates Fire above in the five-element cycle: the lower trigram feeds the upper. Energy moves upward and outward, which is the more productive of the two directions.
Read as a family
Read as family, this is Middle daughter above and Eldest son below. Two siblings, which reads as relationship between equals rather than hierarchy.
The eight trigrams are traditionally assigned family roles — Heaven is the father, Earth the mother, and the remaining six are three sons and three daughters. Which one sits above which is part of how a hexagram is read.
Calculated from the lines
Hexagrams connected to this one
Nuclear hexagram
61 · Inner Truth
Built from lines 2-3-4 and 3-4-5 of this figure — the hexagram hidden inside it. Read as what is happening beneath the surface of the situation.
Opposite hexagram
48 · The Well
Every line flipped. The same situation turned inside out — useful for seeing what you are not currently considering.
Inverse hexagram
22 · Grace
The same figure turned upside down — traditionally read as the situation seen from the other party's side.
None of these are assigned by an author — each follows from the arrangement of lines.
The image
Fire above, Thunder below.
Fire over Thunder: clarity and attachment meeting arousal and shock.
That combination is the whole meaning of hexagram 21. Nothing about it is arbitrary — change either trigram and you get a different hexagram with a different reading, which is why the 64 form a system rather than a list.