Attributed to Aristotle in Diogenes Laertius "The Lives and Opinions of Eminent Philosophers" translated by C. D. Yonge and Henry G. Bohn (p. 188), 1853.
William Goldman (2013). “The Princess Bride: An Illustrated Edition of S. Morgenstern's Classic Tale of True Love and High Adventure”, p.120, Houghton Mifflin Harcourt