According to Mill's Autobiography, On Liberty was first conceived as a short essay in 1854. As the ideas developed, the essay was expanded, rewritten and "sedulously" corrected by Mill and his wife, Harriet Taylor. Mill, after suffering a mental breakdown and eventually meeting and subsequently marrying Harriet, changed many of his beliefs on moral life and women's rights. Mill states that On Liberty "was more directly and literally our joint production than anything else which bears my name." The final draft was nearly complete when his wife died suddenly in 1858. Mill suggests that he made no alterations to the text at this point and that one of his first acts after her death was to publish it and to "consecrate it to her memory." The composition of this work was also indebted to the work of the German thinker Wilhelm von Humboldt, especially his essay On the Limits of State Action. Finally published in 1858 On Liberty was one of Mill's two most influential books (the other being Utilitarianism).