You write something in your diary. Something you haven’t told anyone.
A few days later, someone asks you about it.
“Why would you write something like that?”
You look at them.
“I didn’t tell you.”
“No, but I know.”
You go to your room. The diary is in the drawer where you left it.
Later, you open it.
You look at the pages differently now.
The next time you have something you don’t want anyone to know, you don’t write it down.