Custom and convention
Porter, Cole. "Anything Goes." Anything Goes. Performed by Ethel Merman. 1934, Alvin Theatre, New York, NY, USA.
Plato. Quoted in Lives and Opinions of Eminent Philosophers, written by Diogenes Laertius. c. 240 AD, bk. 3, sect. 86.
Plato. Quoted in The Lives of Eminent Philosophers, written by Diogenes Laërtius, translated by Pamela Mensch, edited by James Miller. Oxford University Press, 2018, bk. 3, sect. 86.
Einstein, Albert. Quoted in The Universe and Dr. Eistein. Written by Lincoln Barnett. Sloane, 1950. Originally printed in Harpers, 1948.
Twain, Mark. The Gorky Incident. 1906.
Twain, Mark. "The Gorky Incident." Letters from the Earth: Uncensored Writings, edited by Bernard DeVoto. Harper Perennial Modern Classics, 2004.
Quoted in On Baptism, Against the Donatists, by Augustine of Hippo
Libosus of Vaga. Quoted in De Baptismo Contra Donatistas [On Baptism, Against the Donatists]. c. 400, bk. 3, ch. 6, sect. 9.
Coke, Edward. The First Part of the Institutes of the Lawes of England. Or, a Commentarie upon Littleton, Not the Name of a Lawyer Onely, but of the Law it selfe. London: Societe of Stationers, 1628, bk. 1, ch. 10, sect. 80.
Catt, Carrie Chapman. "Why We Ask for the Submission of an Amendment." U.S. Senate Committee meeting. 13 Feb. 1900, US Capitol Building, Washington, DC, USA.
Benedict, Ruth. Patterns of Culture. Houghton Mifflin Company, 1934, ch. 1.
Khaldun, Ibn. مقدّمة ابن خلدون [The Muqaddimah]. 1377, bk. 1, ch. 2, sect. 5.