Considered his most important work, Mahbub ul Haq's Reflections on Human Development appeared at the end of his career in international development, and consolidates his revolutionary contribution to the discipline. Haq argues that the goal of any society should be to improve the lives of its citizens; therefore, economic development should support that aim. Economists should use indicators such as life expectancy and education levels to assess a country's overall level of 'human' development so citizens can live lives they value. Thanks to Haq's work, prioritizing human development, rather than pure economic productivity, is now seen as an agreed necessity within the field.