Published in 1859, On Liberty was perhaps John Stuart Mill's finest and most controversial work. Released shortly after his beloved wife, Harriet's death, On Liberty is Mill at his finest arguing for the principles he had espoused over his fifty years of life. Before she died, Mill and his wife carefully analyzed each page of the work, perfecting it to their satisfaction. Mill therefore dedicated this book to his wife's memory, he considered it his most important work.
Much of the impetus for this book was created between dialogues between he and his wife shared. Before their marriage, they would write each other long letters, lamenting the state of affairs in England and the world. One of their main complaints was the declining amount of original, bold thinkers in society, they both saw the numerous advantages in a society that encouraged the pursuit of dreams. This is clearly reflected in On Liberty as Mill denounces society for its need for conformity. Indeed, another issue that instigated some of the theories and commentary in On Liberty was Mill's fear of middle class conformism which plagued him in his entire life's work; this fear was probably instigated by Mill's study of Tocqueville's Democracy in America. The strong presence of Harriet's opinion was also felt in a lot of the issues that Mill supported in On Liberty such as women's rights and educational standards. In his stint in Parliament, Mill was an fervent advocate of these issues, earning a reputation of being a radical liberal.
In nineteenth century England in which Mill lived, there was a struggle between increasing religious strictness and the rebellion that accompanied that strictness. Mill's work was definitely indicative of this struggle as he was not a supporter of religion being treated as a doctrine without the requirement of personal integrity. Mill wrote On Liberty to emphasize one principle: that individuals had absolute freedom to do what he wants if his actions are self-regarding.
The first edition of On Liberty sold out and a second edition followed in late 1859 and a third in 1864. Although the circulation was fairly broad, it met with very harsh reviews and a religious backlash against Mill for referring to the lack of effectiveness of Christianity as a doctrine. Overall, the way that Mill tried to incorporate the importance of individuality with a sense of societal obligation is looked upon as admirable but much of the deductions and reasoning is discounted as faulty theory in today's analyses.