clue
How did a ball of thread become something that helps you find an answer?
What do you notice?
A hint, now
clue
A ball of thread, then
clew
The spelling moved. The yarn is still inside.
A clue is a hint. A clew was a ball of yarn.
People began to use the thread-ball as a picture of finding a way.
If you follow a trail of crumbs, yarn, or notes, you are doing what the old picture of a clew was for. The word moved. The job of guiding stayed.
You can stop here. The word already moved.
Go find a traveling word
The screen was the door.
More ways to look outside