The word 秘书 is formed through a conceptual combination of its two component characters. The first character, 秘 (mì), originally conveys notions of secrecy, confidentiality, or that which is hidden and not public. The second, 书 (shū), fundamentally means writings, documents, or books. Historically, the compound thus literally referred to "confidential documents" or "secret writings". Over time, the meaning shifted metonymically from the confidential materials themselves to denote the person entrusted with handling and managing those sensitive records and communications, evolving into the modern meaning of "secretary", an assistant who deals with private correspondence and administrative duties.