John Stuart Mill (1806–73) was the most influential English language philosopher of the nineteenth century. He was a naturalist, a utilitarian, and a liberal, whose work explores the consequences of a thoroughgoing empiricist outlook. In doing so, he sought to combine the best of eighteenth-century Enlightenment thinking with newly emerging currents of nineteenth-century Romantic and historical philosophy. His most important works include System of Logic (1843), On Liberty (1859), Utilitarianism (1861) and An Examination of Sir William Hamilton’s Philosophy (1865).