closed book, a

A secret, mystery, or puzzle, as in I can't figure her out; she's a closed book to me. This term alludes to information one can't obtain or comprehend (because the book is closed). [Early 1900s]

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Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

The volume spread Before your dazzled eyes, so rich with life, Is a closed book—a fair illumined scroll, Traced in strange characters, unknown to you.