## Sunday 9 May 2021

The post title is a little bit misleading as this is actually the design for a single card, but the best way to use them is to print and use seven of them togheter, hence the name.

The "one card" I already presented is rather easy to use but I wanted something more. I set for myself some requirement for a new card that:

• could generate yarrow stalks probabilites (additional proces for other probabilities would be nice)
• could be usable on its own (one card)
• could be combined with other identical cards to generate a line with a single operation
• could be used with other identical cards to keep track of the lines generated (i.e. removing the need for drawing the hexagram with pen and paper).
• has a table to determine the number of hexagram from the lines

I tried many different design and, in the end, I decided to print some card using this one (front & back):

It's rather cramped but fulfills all my requirements.

Seven cards

To make full use of this design, you need to print seven cards. Note that the dimensions are such that the design will fit in a standard business card. You can print them on regular paper and glue to an old business card; or you can print use some pre-cut specific paper. Or you can print them through a dedicated shop.

You use the cards as follows:

• Pick two cards, flip and turn them at will and pair them as shown in the picture below (forming a sort of "L").
• The front card will tell you if it's a yin or yang line. (look at the top or bottom middle of the card).
• If the two ideograms in the top left corners, one red and the other black, are the same it's a moving line.
• Place the front card so that the line you received is at the bottom (moving lines are those with a red dot on the right).
• Repeat the process other five times, each time laying one card over the other so that the line at the bottom is visible. (see the right side of the picture below)
• Place the seventh card on top of the stack in the opposite direction.
• The stacked cards now show both the primary and secondary hexagrams.
• Use the index on the seventh card (or any other method you like) to get the hexagrams number.

An example will, hopefully, clarify better. Let's go through the six steps needed to cast the hexagram line by line looking at the picture above and focusing on the two ideograms in the top left corners:

1. Same ideograms → Moving line (lay down the card as it is)
2. Different ideograms → Non moving line (lay down the card as it is)
3. Different ideograms → Non moving line (rotate the card before laying it down)
4. Different ideograms → Non moving line (lay down the card as it is)
5. Same ideograms → Moving line (lay down the card as it is)
6. Different ideograms → Non moving line (rotate the card before laying it down)

Probabilities are the same as the yarrow stalk method.

Two cards

If you do not want to bring with you seven cards, you can go with just two. Simply use the same process described above but draw the diagram using pen and paper instead.

One cards

And if two cards are still too much to carry around, you can use just one card with two operations for each line:

• Turn and flip the card at will, orient it with the longer side at the bottom and draw the line you see and the red ideogram you see at the top left corner.
• Turn and flip the card at will, orient it with the shorter side at the bottom and draw the black ideogram you see at the top left corner
• If the two ideogram are the same, it's a moving line.

The hexagram index

It may not be apparent at first sight but the circles in the centers can be used to determine the number of the hexagram. The line at the center is line 1 and you move around by matching the other lines.

Let's say you got hexagam 59 :

Moving from line 1 up, you look at the circle that has a yin line in the center and yang lines around. Then you look top or bottom part of the cirle depending on the third line and so on until you reach the sixth line and get the hexagram number:

It needs a little bit of practice but it's not as difficult as it seems.

You may also think about it as follows:

• Use the two bottom lines to select one of the circles.
• Look for the trigram corresponding to lines 3,4 and 5.
• Use line 6 to select one of the two numbers above the trigram.