Johann Wolfgang von Goethe (1989). “Conversations of German Refugees ; Wilhelm Meister's Journeyman Years, Or, The Renunciants”, p.296, Princeton University Press
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 Bayle Bernard, Samuel Lover (1874). “The Life of Samuel Lover, R. H. A.: Artistic, Literary, and Musical, with Selections from His Unpublished Papers and Correspondence”, p.113