In his principal work, Principles of Political Economy (three volumes, 1893–1901), he closely follows John Stuart Mill in his selection of material, but employs statistical and historical discussion, instead of the abstract reasoning from simple assumption that characterises Mill's work.
In his major work, Principles of Political Economy (published over three volumes between 1893 and 1901), the author adheres to John Stuart Mill’s selection of topics, yet employs statistical and historical analysis rather than Mill’s abstract reasoning based on basic premises.