“Conscience is a mother-in-law whose visit never ends.”
1940s–present, A Mencken Chrestomathy (1949)
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H.L. Mencken 281
American journalist and writer 1880–1956Related quotes

Speech in Chicago, Illinois (29 September 1952)
“Even when there is no law, there is conscience.”
Maxim 237
Sentences, The Moral Sayings of Publius Syrus, a Roman Slave

Source: Father and Child Reunion (2001), p. 187.

“…a bride who is bullied by her mother-in-law will herself become a bad mother-in-law.”
about Ralph Kronig's criticism on Samuel Goudsmit's proposal of a self-rotating electron, inflicting the same reaction to Goudsmit as Kronig had been incurred from Wolfgang Pauli [Tomonaga, Sin-Itiro, translated by Takeshi Oka, The Story of Spin, University of Chicago Press, 1997, 0-226-80794-0, 217]

Captain Francis McCullagh, "The Bolshevik Persecution of Christianity," Dutton and Company, 1924, page 192.
Adressing the court during his political show trial in 1923.
Dido and Aeneas (opera; music by Henry Purcell)

“In matters of conscience, the law of majority has no place.”
Young India (4 August 1920)
1920s