George Santayana, Marianne S. Wokeck, Martin A. Coleman, James Gouinlock (2013). “The Life of Reason or The Phases of Human Progress: Reason in Society, Volume VII, Book Two”, p.64, MIT Press
Aristotle (1890). “Aristotle's Treatise on Rhetoric, Literally Tr. with Hobbes' Analysis, Examination Questions and an Appendix Containing the Greek Definitions: Also, The Poetic of Aristotle, Literally Tr., with a Selection of Notes, an Analysis, and Questions”