when did anne's remember the saying" Peter Has more patience than people"? Explain what she mean by it????

Anne Frank remembered this saying on one of those days when she felt bored and depressed. She did not have any friend, so she was wondering whether she should go out or stay at home. 

"‘Paper has more patience than people" means that one can pour out his/her feelings, emotions and thoughts through writing,without being judged by paper.