TL;DR: Casting the I Ching online is essentially a simulation of tossing three coins six times, each toss yielding one line, beginning with the bottom First line and ending with the top Sixth line, to form a hexagram made of an inner trigram and an outer trigram. The result should be read in three layers: the hexagram image, the line texts, and the changing lines that transform into the changed hexagram, rather than looking up a single fortune or misfortune phrase. Documents on coin casting all stress that this is a reference and reflection tool, not an absolute prophecy, so the reader should use it as a way to view an issue from multiple angles.
What does casting the I Ching online actually involve?
Casting the I Ching online is essentially a simulation of the traditional method of tossing three coins six times, each toss producing one line, with six tosses combined into a complete hexagram made of two single trigrams. The only difference from doing it by hand is that a machine generates the randomness instead of a real coin toss, while the hexagram structure, line order, and method of interpretation stay the same.
According to the presentation of coins and the Tam Tai concept in a collection of I Ching articles, the round coin outside symbolizes Heaven, the square hole in the middle symbolizes Earth, and the hand of the caster represents Man. Heaven, Earth, and Man combine into a single whole, in which the caster's intention is seen as communicating with the movement laws of all things. Three coins are tossed six times to form a hexagram made of an inner trigram and an outer trigram, each toss corresponding to one line, going from the bottom First line up to the top Sixth line.
It should be said clearly from the start: this is the understanding of the I Ching discipline and of divination documents, not a scientific conclusion. Casting is described by those documents as a reference tool, a means to view an issue from multiple angles and seek direction, not an absolute prophecy. The lasting value lies in the reflection and contemplation of the hexagram's meaning.
How does the three-coin casting process unfold?
The heads/tails convention and how lines are counted
Before casting, the reader needs to fix a constant convention for heads and tails, for example the side with characters is yang and the blank side is yin, or the reverse, as long as that convention is kept through all six tosses. Documents on coin casting stress that three coins of the same material and size are enough; using antique coins such as Kangxi or Qianlong is not required, and only adds a layer of historical and cultural meaning. More important is a clear convention and strict adherence to the process.
Each toss of three coins produces a combination, from which one line is determined to be a yang line (solid) or a yin line (broken), and whether that line is a changing line. After six tosses, recording the results from bottom to top, one obtains a six-line hexagram.
Recording lines from the bottom up and assembling the hexagram
The six lines are recorded in order from the bottom First line to the top Sixth line. The lower three lines form the inner trigram, the upper three form the outer trigram. From these two single trigrams, the reader looks up the name of the doubled hexagram, for example Thủy Hỏa Ký Tế or Lôi Hỏa Phong.
One example appears in the collection of I Ching articles: suppose one casts Thủy Hỏa Ký Tế, then finds that the fourth and fifth lines are both changing lines, so those two lines transform and form the hexagram Lôi Hỏa Phong. In that situation, Thủy Hỏa Ký Tế acts as the primary hexagram, indicating that matters have reached completion, while Lôi Hỏa Phong is the changed hexagram, foretelling the direction of development or change about to unfold. By grasping this transformation, the caster gains a fuller view of the situation.
A few practical situations when casting
According to experiences recorded in the collection of I Ching articles, in these situations recasting is not required; it is enough to look at the heads or tails of the coin where it is found. To reduce inconvenience, people often choose a clean flat surface such as a table or plate for casting. This flexibility shows that what is considered essential still lies in the caster's intention and level of concentration, not in outward form.
Why does I Ching casting require reading both the hexagram and the lines?
Many people looking at a hexagram pay attention only to the line text and the fortune or misfortune judgment, but overlook that the Small Image Commentary is the intermediate layer of explanation between the hexagram image and the line text. According to the collection of I Ching articles cited, the Small Image Commentary is like a teacher showing the reader why this line says that holding to the right path is good while that line says bad. Without this layer, the line text becomes rigid and easily misread as a vague prophecy.
One example given is the hexagram Phong Trạch Trung Phu: the Small Image Commentary helps one understand why the Ninth Five line has words about trust binding closely, because it is a central and correct yang line, in the ruler's position, carrying the image of sincerity spreading. If this layer of explanation is ignored, the reader easily falls into superstitious divination and loses the philosophical value and practical application of the I Ching.
The Small Image Commentary also forces the reader to think by the logic of transformation: line position, yin-yang nature, and the relationships between lines. Once one understands how this layer casts each line text onto the hexagram image, the reader no longer sees the I Ching as a mysterious book, but uses it as a tool for analyzing situations to make daily decisions.
What does the Ninth Two line of the Qian hexagram show about reading a specific line?
In the Qian hexagram, the Ninth Two is the only line bearing the name "manifest dragon," meaning the dragon has shown its head, unlike the First Nine which is still hidden in the deep. The noble person at that moment has just begun work, bringing talent and virtue to benefit the world. This line is special not only for the image of the manifest dragon, but also for the relationship "favorable to see the great person," meaning the meeting with a great person.
Based on the collection of I Ching articles cited, in this relationship the great person is not only the Ninth Two itself but also the one capable of cooperating with the Ninth Two to build a great undertaking. The same line, the same text, can be read in two directions: inward is self-improvement to be worthy of the position, outward is finding a suitable companion.
According to a modern interpretation also drawn from this collection, success comes not only from effort but also from the right timing. A salesperson catching a trend early, an engineer adding new skills as the industry grows, a manager trimming the apparatus when the economy is difficult, all are ways of adapting at the right moment to one's own circumstances. This is the interpretation of the modern writer, not the original text of the line, so it should be kept separate when reading.
When online casting gives an unfavorable hexagram, how should it be understood?
An unfavorable casting result does not mean things will certainly fail; in the reading of divination books, it is a signal reminding the reader to consider timing and readiness. The book Khổng Minh Thần Toán, in its discussion of a hexagram in the middle-lower group, remarks that when one falls into hardship one should save, economize even small amounts, and spend according to circumstance; if one is free and unrestrained, spending wastefully, then once money has gone it is hard to return. That remark also reminds the person who receives this hexagram to be cautious and not overspend.
Note that this is the interpretation of one specific book, tied to one specific hexagram in that book's system, not a general rule for all hexagrams. Different casting systems have different hexagram tables and judgments; even for the same hexagram, the reading changes with the changing lines and with the reader's specific question.
How do casting and interpretation schools differ?
| Method | How the hexagram is formed | Main unit of interpretation | Notes |
|---|---|---|---|
| Yarrow stalk divination | Use a set of 50 yarrow stalks, pray, then divide and count by procedure | Hexagram and lines | Phan Kế Bính records in Việt Nam phong tục that the old I Ching divination had two ways: turtle divination and yarrow stalk divination |
| Three-coin tossing | Toss three coins six times | Primary hexagram, changing lines, changed hexagram | Common in today's collections of I Ching articles |
| Liu Yao | Cast, then place the Self, Other, six spirits, five elements | Lines, Self and Other, date and month | Has its own layer of conventions, not just reading the hexagram text |
| Divination by sound, tiles, rice, flowers and leaves | By each folk method | Depends on method | Listed by Phan Kế Bính in Việt Nam phong tục |
Phan Kế Bính, in Việt Nam phong tục (published as a book in 1915), records that I Ching divination had only two ways, turtle divination and yarrow stalk divination, while later diviners elaborated yin-yang and five-element reasoning to add many methods such as divination by sound, by tiles, by rice, by flower, leaf, and grass branches. He also notes that our customs, in practice, roughly retain the following few methods, among them thi bốc, the yarrow stalk method. This is a record by an early 20th-century author about customs of his time, not a complete classification for all periods.
On the yarrow stalk method, Phan Kế Bính describes: to divine, one first needs a set of 50 yarrow stalks cut evenly, each about three or four tấc long, then stored in a clean and careful bag; when a matter arises, one brings out the set and places it on a stand, reverently praying to the spirits for guidance. This description shows that preparation and reverence are placed on par with the technical operation.
What misunderstandings should be avoided when reading online casting results?
According to documents on coin casting, when the casting process ends, what matters is not which hexagram is received, but how we interpret and apply the hexagram's message to real life. Each line and each hexagram carries its own meaning, expressing the movement laws of all things. Grasping the connection between Yin and Yang, Tam Tai, and the transformation of lines helps users better exploit the value of this method.
Three common misunderstandings:
- Treating the casting result as a fixed verdict. The documents all stress this is a reference tool and suggestion for making decisions, not an absolute prophecy.
- Looking up only the fortune or misfortune judgment while ignoring the hexagram image and the intermediate layer of explanation. This easily leads to misreading the line text as a vague oracle.
- Blurring the systems. The judgments of the book Khổng Minh Thần Toán cannot be used for hexagrams in the Liu Yao system, and vice versa. Each system has its own convention table.
Origin and place of the I Ching among divination disciplines
A record in a book on Tử Vi states that Tử Vi đẩu số is a school belonging to I Ching studies, and that this school's root thought lies in the I Ching, one of the Five Classics that tradition attributes to Confucius's editing. The same record remarks that the I Ching was at first only a divination book, later becoming a philosophical work containing many deep thoughts. Note that this is the opinion of one specific document, and the tradition attributing the I Ching to ancient authors is legendary: modern research does not consider the chain of Fu Xi drawing trigrams, King Wen, the Duke of Zhou, and Confucius writing the Yi to be proven historical events.
Also according to this record, the I Ching was not written by one person but supplemented by many people over many generations, and before being edited it had begun to take shape as the eight trigrams. The eight single trigrams are Qian, Kun, Zhen, Xun, Gen, Kan, Li, Dui, with Qian meaning Heaven, Kun Earth, Li fire, Kan water, Gen mountain, Dui lake, Xun wind, Zhen thunder. Based on the description, the Yi begins from the Two Modes (broken and solid lines), producing the Four Images, then the Eight Trigrams. Tradition attributes the establishment of the eight trigrams to Fu Xi, but the I Ching text itself has many contradictory passages that led later generations to propose various hypotheses.
According to this document, in terms of value, the method of thinking is the greatest thing the Yi leaves to the world, while divination is what helped it survive with the world. That assessment is the writer's view, worth consulting but not to be read as a general conclusion of researchers.
Nhật Nguyệt's suggestions when using an online casting tool
If you use an online casting tool, first define a clear question and a fixed heads/tails convention, then record all six lines in order from the bottom up. Read the result in three layers: the hexagram image speaks of the general context, the line text speaks of your position in that context, and the changing lines and changed hexagram speak of the direction of movement. Do not use the result to replace your own decisions in important matters such as health, finance, or law; treat it as a mirror for self-questioning. And if an answer sounds too certain, remember that the casting documents themselves say this is only a reference tool.
