Propound why a library is said to be the memory of the human race?

A library is known to be the memory of the human race, because the library contains a thousand books about the history of mankind, from the beginning of evolution. The library contains knowledge of the past that pertains to a past memory that once existed and now only remembered. Almost every detailed information in the past is found in the library, which is why it is considered to be the memory of the human race.