Nassau William Senior (1790-1864) - economist, critical essayist and government adviser - was a highly original classical economist in the era between Ricardo's Principles of 1817 and Mill's Principles of 1848. He was the first Professor of Political Economy at Oxford, and in his published works he made original contributions to the theory of value, rent, population, money, and international trade. Senior was an active proponent of laissez-faire. Although Senior did not achieve the originality and influence of the leading economists of the classical school - Smith, Ricardo, and Malthus - he did make an enduring contribution on the development of economics. John Stuart Mill took much effort to respond to Senior.