From the Introduction In his Autobiography, Mill predicts that the essay On Liberty is "likely to survive longer than anything else that I have written." He goes on to say that the essay is the expression of a "single truth: " "the importance, to man and society, of a large variety of types of character, and of giving full freedom to human nature to expand itself in innumerable and conflicting directions." In the essay itself, Mill defines his subject as "the nature and limits of the power which can be legitimately exercised by society over the individual." He defends the absolute freedom of individuals to engage in conduct not harmful to others, and the near-absolute freedom to express and discuss opinions of all kinds. Mill's essay survives, as he had predicted, because his powerful message is still widely rejected by the powerful, and by those who continue to seek power over the lives of others.