What makes a line move
When you throw three coins, each toss gives you a number: 6, 7, 8 or 9. These numbers tell you what kind of line you have drawn. A 7 is a solid, straight line called young yang. An 8 is a broken line called young yin. These are stable lines that stay as they are. But a 6, old yin, is a broken line that is full and ready to change. A 9, old yang, is a solid line that is full and ready to change. These are the moving lines, the heart of the I Ching changing lines.
Old yin (6) and old yang (9) are called "old" because they have reached the end of their cycle. Think of them as ripe fruit ready to fall and become something new. A young line is like a green fruit still on the branch. The moving lines are where the action is. They show you the forces in your situation that are shifting, the parts that cannot stay still. When you see a 6 or a 9 in your cast, pay close attention. Those lines carry the energy of change.
When you understand which lines move, you begin to see the deeper story your cast is telling.
From one hexagram to the next
Every moving line flips to its opposite. A moving yin line (6) becomes a solid yang line. A moving yang line (9) becomes a broken yin line. The lines that are young, the 7s and 8s, stay exactly the same. When you flip all the moving lines, you build a second hexagram. This second hexagram is called the relating hexagram, or 之卦. It shows where your matter is heading next.
Think of the first hexagram as a photograph of your situation right now. The moving lines are the parts of that picture that are already in motion. They are like seeds that have started to sprout. The second hexagram is what that sprout can grow into if things follow their natural course. It is not a prediction of what will happen. It is a picture of the tendency, the direction the situation wants to move.
The first hexagram and the second hexagram are linked. The moving lines are the bridge between them. Their texts give you the specific advice or insight for the change. Sometimes only one line moves, sometimes several, sometimes all six. The more moving lines you have, the more fluid and unsettled your situation is. With fewer moving lines, the change is more focused and specific.
A worked example
Imagine you ask a question and the server throws the coins for you. The values come up from the bottom line up: 7, 8, 9, 7, 6, 8. The bottom line is a 7, a solid young yang line that stays. The second line is an 8, a broken young yin line that stays. The third line is a 9, a solid old yang line that moves. The fourth line is a 7, solid and stays. The fifth line is a 6, a broken old yin line that moves. The top line is an 8, broken and stays.
Your first hexagram is hexagram 55, named 豐, Abounding. This is the picture of your situation now. Two lines move: line 3 and line 5. Line 3 is the 9, old yang, and its text says: "He makes the canopy very full, and at midday he sees the small stars. He breaks his right arm. No blame." This line speaks of a time when abundance itself creates confusion. You have so much that you lose sight of what is clear. The broken arm is a loss that brings no blame, just a necessary limitation.
Line 5 is the 6, old yin, and its text says: "Those who come bring brightness. There is celebration and praise. Good fortune." This line is hopeful. Help arrives, and it is welcomed. The contrast between line 3 and line 5 shows the tension in your situation: confusion at one level, good news at another.
Now flip the moving lines. Line 3 changes from a solid line to a broken line. Line 5 changes from a broken line to a solid line. The other lines stay the same. Your second hexagram is hexagram 17, named 隨, Going With. This is where things are heading. The name itself tells you the direction: you are learning to go with the flow, to follow what is moving naturally.
How to read a cast with moving lines
Start with the first hexagram. Read its name and general meaning. This is the main picture of your situation. Then look at each moving line one by one. Read its text carefully. These lines are the specific message for you. They tell you what is changing and how to act. If a line has a judgment like "good fortune" or "no blame," that is part of the guidance.
After you have read the moving lines, turn to the second hexagram. Read its name and general meaning. This is the direction your situation is tending toward. Do not read the lines of the second hexagram. Only the first hexagram's moving lines matter. The second hexagram is a whole picture of where you are going, not a set of detailed steps.
Put it all together. The first hexagram shows your starting point. The moving lines show the forces in motion and what they ask of you. The second hexagram shows where things are heading. The whole cast is a story from beginning to next stage, with the moving lines as the turning points.
When no line moves
Sometimes you throw the coins and every line is a 7 or an 8. No 6s, no 9s. This means no line moves. Your cast has only one hexagram, with no second hexagram. This is a steady picture of your situation. Nothing is forcing a change right now. The hexagram speaks directly to your question as a whole, and you read it as a complete answer.
When no line moves, the situation is stable. The energy is not shifting. This can be a relief if you need clarity without complication. It can also be a sign that you need to be patient and let things settle. Read the hexagram's name and its meaning for your question. Take it as the full message.
The I Ching is for reflection and entertainment. It helps you look at a question from a new angle and does not decide for you. Whether you have moving lines or not, the cast offers a way to think more deeply about what you face.
For reflection and entertainment.