The Life of Reason: The Phases of Human Progress is a book published in five volumes from 1905 to 1906, by Spanish-born American philosopher George Santayana. It consists of Reason in Common Sense, Reason in Society, Reason in Religion, Reason in Art, and Reason in Science. The Life of Reason is sometimes considered to be one of the most poetic and well-written works of philosophy in Western history. To supply but a single example, the oft-quoted aphorism of Santayana's, "Those who cannot remember the past are condemned to repeat it," may be found on p. 284 of Reason in Common Sense.