be a closed book
be a closed book
To be difficult to know or understand. She's such a private person that I don't know much about her. I guess she's a closed book. I'm a scientist through and through, so art has always been a closed book to me.
See also: book, closed
Farlex Dictionary of Idioms.
- a closed book
- closed book, a
- I know
- Don’t I know it!
- don't I know it
- as we know it
- before you know it
- as you know
- can't say as I do
- (I) can't say as I do