" Messieurs and Mesdames, I am a student of psychology. All through this case I have looked, not for the bad-tempered man or woman, for bad temper is its own safety valve. He who can bark does not bite. No, I have looked for the good-tempered man, for the man who is patient and self-controlled, for the man who for nine years has played the part of the under dog. There is no strain so great as that which has endured for years, there is no it resentment like that which accumules slowly. "

― Agatha Christie