Some history
The first users of the I Ching consulted by sorting yarrow stalks – the yarrow being a sacred plant imbued with spiritual power, and thus naturally right for seeking the truth. Later, as the I Ching became more popular and widely used, a simpler method was invented using three coins. Exactly when it was invented is not known, but it became popular during the twelfth to thirteenth centuries AD. The original yarrow method has been lost, but it was reconstructed, at about the same time as the coin method was gaining in popularity, by Chu Hsi. (You can learn the yarrow method of consulting the I Ching here.) In many I Ching books, you will find the yarrow method referred to as the ‘authentic’, original way to consult the I Ching. While its roots do go back further – to long before the invention of coinage in China – we have no way of knowing whether the method we use now is the original.
So from the point of view of ‘authenticity’, there is not much to choose between yarrow and three coins. The coin method has the great advantage of speed and convenience: you do not need any special equipment, just three identical coins. (You can buy Chinese coins if you wish, of course, but this isn’t necessary. After all, the first users didn’t buy special coins!) It reflects the intensely realistic, practical nature of the I Ching, which is not meant to be difficult to use.
The yarrow method is different in two ways. Firstly, it sets the occupation of consulting the I Ching apart from ordinary life and opens up a sense of connection to the ancient diviners. It forces you to take time over it and to concentrate – for many people, it becomes an important ritual. On the other hand, ritual can also become a distraction from the essential: it depends on the individual.
Secondly, over time it gives subtly different results from the coin method. This is because the mathematical odds of receiving each of the four kinds of line are slightly different. Briefly, while you are equally likely to receive a moving line with either method (1 in 4 lines), with the yarrow you are more likely to get moving yang (solid) lines and stable yin (broken) ones.
Here is a comparison of the odds of receiving each kind of line under the two systems:
| Line | Value | Three coin | Yarrow |
|---|---|---|---|
 | 7 | 3 in 8 | 5 in 16 |
 | 8 | 3 in 8 | 7 in 16 |
 | 9 | 1 in 8 | 3 in 16 |
 | 6 | 1 in 8 | 1 in 16 |
The yarrow odds seem to reflect the more dynamic nature of yang and the greater stability of yin, and some people find this give a greater depth and subtlety to their readings. I’ve certainly become used to them myself.
But how important is probability to the I Ching’s answers? How would you calculate the probability of receiving the exact same answer twice in succession when you asked the same question twice? Or of receiving what was your primary hexagram as the relating hexagram and vice versa when you ask about the same situation from the other person’s perspective?
The simple answer is that this cannot be done. Of course you can calculate the probability of receiving the same answer twice in succession. (Well, I can’t, but maybe you can!) But there is no way to include the question in your calculations. The whole element of meaning is missing.
So in the end it comes down to the question of what works best for you, and most clearly enables you to concentrate on the divination. But thanks to the people who first worked out the probabilities, we now have the choice of using the yarrow odds in newer, simpler methods: with sixteen tokens, or just with two coins.
(And if you’re interested in exploring different ways to consult the I Ching, but not particularly concerned with probabilities, you might be interested in these other methods.)