Nightingale's passionate commitment to statistics was based on her faith in a god of order, who created a world that ran by law. God's laws could be known through research, as a result of which suitable interventions to better the world could be applied. Statistics were a vital component in her holistic approach to health care as a system. They served both to indicate serious problems and to assist in policy making, and then again to monitor the effects of the new policies. She pioneered the use of evaluative statistics and saw reforms achieved as a result of her advocacy. This article explores three key aspects selected from Nightingale's more than 40 years of applied statistical work: her adaptation of Quetelet's methodological foundations, the use of statistics in monitoring public health care systems, and her pioneering study of maternal mortality in childbirth.