Title of book (1969), taken from the last line of "Sympathy" by Paul Laurence Dunbar in Lyrics of Hearthside (1899). Cf. Oxford Dictionary of Quotations (1979) 567:10
George Santayana, Marianne S. Wokeck, Martin A. Coleman, James Gouinlock (2015). “The Life of Reason Or The Phases of Human Progress: Reason in Art, Volume VII, Book Four”, p.118, MIT Press