I Ching Hexagram 18
Hexagram 18: Gu (蛊)
Composed of 巽 (Xun) below and 艮 (Gen) above · decay · repair · correction · inheritance
The Judgment
蛊：元亨，利涉大川。先甲三日，后甲三日。
Gu (Decay That Must Be Repaired): great, it flows. Favorable for crossing the great water. Three days before the day of 甲, and three days after.
Translation notes
- 蛊: Wilhelm renders "Work on What Has Been Spoiled" — The character is a vessel (皿) holding a venomous thing (虫), and the earliest explanations take it as the snake put away to wait for the right moment. That root is worth keeping, because it means the damage is not an accident but something that was stored and allowed to sit. The modern reading of 虫 as 'bug' gives a useful second image — infestation, spreading decay — but the fixing is the real subject, which is why all six lines are about who takes the job and what it costs them.
- 先甲三日: Wilhelm renders "three days before the beginning, three days after" — 甲 is the first of the ten heavenly stems, so it is a day-count — the opening day of a ten-day cycle. The counsel is about timing: prepare before the appointed day and hold after it, rather than starting on it. It is a small piece of administrative discipline buried in the middle of a decay hexagram, and it is why the judgment bothers to mention it twice.
The judgment above quotes the classical Chinese of the Zhou Yi (public domain); the English gloss and modern reading are our own. Compare with James Legge's The I Ching (Sacred Books of the East, Vol 16) , 1882 (public domain).
Quick Answers
Is hexagram 18 (Gu) good or bad?
Bad as a condition, good as a task. Gu is one of the twelve unfavorable hexagrams, and it describes decay that has been left in place. But it is not static: the judgment says great success, and all six lines are about taking on the repair. So the answer depends on whether you are the person with the standing to fix it. If you are, this is one of the most useful hexagrams in the book.
What does hexagram 18 (Gu) mean in love?
It means a repair, specifically. The hexagram is about something that deteriorated quietly, and in a relationship that is almost always an old thing nobody wants to name. The good move is 九三: do the repair from a position of strength and expect some criticism for having touched it. The bad move is 六四 — shielding your partner, or the appearance of the relationship, instead of the problem underneath it.
What happens when line 6 of hexagram 18 (Gu) changes?
Line 6 is 上九, the man who repaired the decay and then does not go back to court. Flip it and Gu becomes Hexagram 46 (Sheng, Pushing Upward): the withdrawal becomes a slow ascent. Concretely, having finished the inherited job, the text no longer holds you there — you get a new, gradual rise instead of the old obligation. In a relationship this reads as someone who completed the repair and is then available for something new, rather than returning to the pattern.
The Six Lines
Read your line of interest below. Lines are read from the bottom (line 1) to the top (line 6). A changing line means the hexagram is transforming — see the related hexagrams at the bottom.
初六
干父之蛊，有子，考无咎，厉终吉。Taking on the father's decay. There is a son; the father is without blame. Dangerous, but good in the end. Changing into Hexagram 26 (Da Chu, Great Taming).
The bottom line, and it is already a family job: a son inherits the mess and repairs it while the blame sits with the predecessor, and the operative word is 干, to take up and work at it — so expect it to be uncomfortable while you are in it, because the good is at the end of the process, not inside it.
九二
干母之蛊，不可贞。Taking on the mother's decay. It cannot be held to. Changing into Hexagram 52 (Gen, Keeping Still).
A subtle one, because the second line cannot be sustained: it warns against taking on a long, well-meant, inherited obligation that cannot actually be completed, where the obligation and the care are both real and neither of those facts makes it possible.
九三
干父之蛊，小有悔，无大咎。Taking on the father's decay. A small regret, no great blame. Changing into Hexagram 4 (Meng, Youthful Folly).
The same job taken from a more visible position, and the verdict is milder — a small regret, no serious fault — so do it and expect criticism from people with an interest in the status quo, understanding that the great blame is what you avoid by staying inside the problem.
六四
裕父之蛊，往见吝。Easing the father's decay. Going forward is seen with regret. Changing into Hexagram 50 (Ding, The Cauldron).
A yin line in a strong position choosing sympathy over repair, and covering a problem for the sake of the person who created it, or for the sake of appearances, is also how decay continues — the line's verdict on pressing forward is 吝, and this is the one real failure in the hexagram.
六五
先甲三日，后甲三日。Three days before the day of 甲; three days after. Changing into Hexagram 57 (Xun, The Gentle).
The judgment's schedule, repeated on its own line: prepare before the deadline and hold after it, since repairing an old problem succeeds or fails on whether it is started early and checked afterwards.
上九
不事王侯，高尚其事。He does not serve the prince and lord. He keeps his own affair loftily. Changing into Hexagram 46 (Sheng, Pushing Upward).
The exit line, and the one most often quoted: at the top, the person who repaired the decay does not go back to court, which is a real permission not to resume the relationship that produced the problem once the job is done.
Hexagram 18 in Love, Career & Decisions
Love & Relationships
Worth looking at, because this hexagram is about something that was tolerated for a long time. Partnered: it reads as a repair conversation — not a fresh start and not a romance, but a specific old thing that has quietly deteriorated. 九三 is the good line here: do the uncomfortable repair from a position of some standing, expect a little criticism, and accept it. 六四 is the failure, which is protecting your partner, or the image of the relationship, instead of the actual thing underneath. Single: the pattern is not a person but a habit of your own that has decayed and now needs work.
Name the one thing in the relationship you have both been stepping around, and put a date on dealing with it.
Career & Work
Unfavorable for starting something new, favorable for fixing something old. Answer early: yes to the inherited mess — the legacy system, the undocumented process, the commitment that keeps sliding. No to launches. The career version of 九三 is the interesting case: a visible person with enough standing to repair something important, who will attract criticism precisely for having touched it. Line 5's advice is operational and cheap — start before the deadline, then check. If your work here is only making a failing thing look acceptable, that is 六四, and the hexagram calls it regrettable.
Take the neglected system nobody wants to own, start the fix a week before it is due, and report on it afterwards.
Making a Decision
YES for repair, NO for anything new. The judgment supports crossing the great water, so a large undertaking is fine — but it is talking about one built on repair rather than invention. The condition is line 4: if the only available version of this is making an inherited problem less visible, the answer is no. What to watch is where the problem came from: if it came from someone you still depend on, expect the small regret of line 3, and treat that as a known cost rather than a reason to stop. And begin early — the hexagram is unusually insistent about the three days before.
Favorable for taking on a deteriorating situation, conditional on actually fixing it rather than concealing it — and start before the deadline you were given.
Health & Wellbeing
Stagnant and in need of clearing out. Gu's energy is sediment, and the image is a low enclosed place where something has been sitting too long. The mood that goes with it is dull and slightly ashamed, which is very close to the tone of 六四 covering things up. The text's own treatment is scheduling: three days before, three days after. For entertainment and reflection only, not medical advice.
Clear one neglected corner today and write down two dates — when you will begin the rest, and when you will check whether it worked.
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