It was at this instant that I was visited by the idea of writing the book which ultimately became The Old Wives' Tale. Of course I felt that the woman who caused the ignoble mirth in the restaurant would not serve me as a type of heroine. For she was much too old and obviously unsympathetic. It is an absolute rule that the principal character of a novel must not be unsympathetic, and the whole modern tendency of realistic fiction is against oddness in a prominent figure. I knew that I must choose the sort of woman who would pass unnoticed in a crowd.