Lives of Wives (London: Cassell, 1939)
“THEODOTUS: Caesar: you are a stranger here, and not conversant with our laws. The kings and queens of Egypt may not marry except with their own royal blood. Ptolemy and Cleopatra are born king and consort just as they are born brother and sister.
BRITANNUS (shocked): Caesar: this is not proper.
THEODOTUS (outraged): How!
CAESAR (recovering his self-possession): Pardon him, Theodotus: he is a barbarian, and thinks that the customs of his tribe and island are the laws of nature.”
Act II; sometimes paraphrased as: The customs of your tribe are not laws of nature.
1890s, Caesar and Cleopatra (1898)
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George Bernard Shaw 413
Irish playwright 1856–1950Related quotes
Source: William Stringfellow: Essential Writings (2013), "Jesus the Criminal" (1969), pp. 65-66

“Forgive him, for he believes that the customs of his tribe are the laws of nature!”
Act II; sometimes paraphrased as: The customs of your tribe are not laws of nature.
1890s, Caesar and Cleopatra (1898)
Variant: Pardon him, Theodotus: he is a barbarian, and thinks that the customs of his tribe and island are the laws of nature.
Context: THEODOTUS: Caesar: you are a stranger here, and not conversant with our laws. The kings and queens of Egypt may not marry except with their own royal blood. Ptolemy and Cleopatra are born king and consort just as they are born brother and sister.
BRITANNUS (shocked): Caesar: this is not proper.
THEODOTUS (outraged): How!
CAESAR (recovering his self-possession): Pardon him, Theodotus: he is a barbarian, and thinks that the customs of his tribe and island are the laws of nature.

Big Red Son, p. 9
Consider the Lobster (2007)
Context: Nor let us forget Vegas's synecdoche and beating heart. It's kitty-corner from Bally's: Caesar's Palace. The granddaddy. As big as 20 walmarts end to end. Real marble and fake marble, carpeting you can pass out on without contusion, 130,000 square feet of casion alone. Domed ceilings, clerestories, barrel vaults. In Caesars Palace is America conceived as a new kind of Rome: conqueror of its own people. An empire of self.
Ch 29
A Canticle for Leibowitz (1959), Fiat Voluntas Tua

“And to emphasize the bad name Caesar had won alike for unnatural and natural vice, I may here record that the Elder Curio referred to him in a speech as: "Every woman's man and every man's woman."”
At ne cui dubium omnino sit et impudicitiae et adulteriorum flagrasse infamia, Curio pater quadam eum oratione omnium mulierum virum et omnium virorum mulierem appellat.
Source: The Twelve Caesars, Julius Caesar, Ch. 52

§ 228
The Reasonableness of Christianity (1695)

Page 91
Publications, An Enduring Love: My Life with the Shah (2004)