John Stuart Mill was a prominent English philosopher and political economist. Mill is considered to have been one of the most important figures in the history of liberalism, and he contributed greatly to social theory and political theory. Mill was also notable for being the first Member of Parliament to support women's suffrage. On Liberty, published in 1859, is Mill's most famous work. The book is considered to be one of the greatest works in social and political philosophy. Utilitarianism, published in 1863, is one of Mill's most important works as it popularized utilitarian ethics. Mill used many of the same ideas introduced by Jeremy Bentham and expanded on them. The Subjection of Women, published in 1869, is a long essay that may have been co-written by Mill's wife Harriet Taylor Mill. Mill believed that the inequality of women should be a thing of the distant past, a view which was shared by very few. Mill argued that having half the human race being unable to contribute much to society was a major hindrance to the development of mankind.