The last step "Documentation(B)" is a task of making an explanation based on this illustration.

In the illustration, the information is arranged in a two-dimensional space. However, to make a table of contents of a book, we must convert it to a tree structure. To make an explanation, we must convert it to a one-dimensional sequence of words.

This format conversion task is useful. You may find a gap when you try to make a connected story.

An illustration is suitable for grasping the overall picture roughly. However, often you do not notice ambiguity of connection. You notice the ambiguity by writing sentences.

Suppose A and B are placed near each other in the illustration. You may feel it is like a causal relationship at this stage. However, when you convert it to a sentence "because of A, it is B," you may feel "is that really true?"

This doubt is an opportunity for learning. You noticed your blind spot. There should be missing pieces, which you did not write yet. You got a chance to fill it.

On the other hand, some people may think that illustration is not necessary because sentences can describe relationships more clearly.

However, when you are focusing on the details of the sentence, you tend to lose sight of the overall balance.

The illustration gives you a bird's-eye view. It gives you a rough map. The documentation gives you a worm's-eye view. It gives you a locally close-up point of view. Worms are steadily progressing while paying attention to details. Using both eyes is important.

After this KJ method process, you get a one-dimensional sentence. You made it from 100 pieces of fragmental information. Once you make a sentence, you can explain it to other people and get feedback. It is an opportunity for learning.

Also, as I explained in (4.5.3.3) Make teaching materials, your memory becomes strong by trying to explain to others. Furthermore, you can use the sentences as teaching material for your review in the future.