Book Idioms An open book If a person is an open book, it is easy to know how they feel and what they think about things. A closed book If a person is a closed book it is difficult to know how they feel and what they think about things. Read someone like a book When you can easily guess what someone is thinking or feeling. Book worm Someone who reads a lot.
Don’t judge a book by its cover Not forming an opinion of someone just from their appearance. In someone’s good books To be in someone's good books means that they are pleased with you.