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, so art will always be a closed book to me.

be a closed book

to be something that you know or understand nothing about (usually + to ) I'm afraid physics will always be a closed book to me.

Common Names:

Name	Pronounced	Usage
Gordan	GOR-dahn (Serbian, Croatian)	Serbian, Croatian, Macedonian
Nikomachos	-	Ancient Greek
Baudelio	-	Spanish
Enos	EE-nahs (English)	Biblical, Biblical Latin, Biblical Greek
Demetrio	de-ME-tryo	Italian, Spanish
Venera	vye-NYE-rah (Russian), vee-NYE-rah (Russian)	Russian, Bulgarian, Albanian