Why would a personal diary like Anne's be considered an important historyical record?

Anne's diary is important because it is a piece of history from someone who lived that history. Anne was an eye witness to the Holocaust, and she experienced it first hand. She was an innocent who had her innocence taken away. She saw the fear, the injustice, the anger, the loss of faith, the selfishness all up front and personal. We can read the accounts of historians, but those accounts will never have the personal bond we have with Anne.