All writers who have any practical and permanent contribution to make to the guidance of human conduct, perceive and proclaim some aspect or other of the philosophy of utility.  They may not explicitly recognize happiness as the end of life,–indeed they may explicitly repudiate it,–but their instinct enables them to identify means, even if the end eludes them.

James MacKaye, Thoreau: Philosopher of Freedom, New York, 1930, p. ix