Question

Why does Anne say "Paper is more patient than people"?

Answer 1

As she has no one, she could have talked too so she makes paper as her confidant. It listens to her with no argument and interruption, and keeps all her secret. 

Answer 2

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Anne believes that paper has more patience than people because it listens to her more patiently and silently. It does not react like other people and also because she can confide in her diary all her secrets.