Mill's mission in writing On Liberty can perhaps be best understood by looking at how he discussed his work in his Autobiography. Mill wrote that he believed On Liberty to be about "the importance, to man and society, of a large variety in types of character, and of giving full freedom to human nature to expand itself in innumerable and conflicting directions." This celebration of individuality and disdain for conformity runs throughout On Liberty. Mill rejects attempts, either through legal coercion or social pressure, to coerce people's opinions and behavior. He argues that the only time coercion is acceptable is when a person's behavior harms other people--otherwise, society should treat diversity with respect.