The camel's nose is a metaphor for a situation where the permitting of a small, seemingly innocuous act will open the door for larger, clearly undesirable actions.
This bill and the foregoing remarks of the majority remind me of an old Arabian proverb: "If the camel once gets his nose in the tent, his body will soon follow." If adopted, the legislation will mark the inception of aid, supervision, and ultimately control of education in this country by the federal authorities.
According to Geoffrey Nunberg, the image entered the English language in the middle of the 19th century. An early example is a fable printed in 1858 in which an Arab miller allows a camel to stick its nose into his bedroom, then other parts of its body, until the camel is entirely inside and refuses to leave. Lydia Sigourney wrote another version, a widely reprinted poem for children, in which the camel enters a shop because the workman does not forbid it at any stage.
The 1858 example above says, "The Arabs repeat a fable", and Sigourney says in a footnote, "To illustrate the danger of the first approach of evil habit, the Arabs have a proverb, 'Beware of the camel's nose.'" However, Nunberg could not find an Arab source for the saying and suspected it was a Victorian invention.
An early citation with a tent is "The camel in the Arabian tale begged and received permission to insert his nose into the desert tent." By 1878, the expression was familiar enough that part of the story could be left unstated. "It is the humble petition of the camel, who only asks that he may put his nose into the traveler's tent. It is so pitiful, so modest, that we must needs relent and grant it."
A 1909 essay by John B. West, founder of the West legal classification system, used the metaphor to describe the difficulty of trying to insert an otherwise innocuous set of facts, into a rigid legal system:
three excellent digesters  spent an entire day in disagreeing as to whether seal fishery cases should be classified under the topic 'Fish' or that of 'Game' .... It is the old story of the camel's head in the tent. What seems at first a plausible pretext for forcing some novel case or new principle into a topic or subdivision to which it does not naturally belong, leads to hopeless confusion.
The phrase was used in Reed v. King (193 CA Rptr. 130 - 1983): "The paramount argument against an affirmative conclusion is it permits the camel's nose of unrestrained irrationality admission to the tent. If such an 'irrational' consideration is permitted as a basis of rescission the stability of all conveyances will be seriously undermined." The case in question involved a plaintiff suing because the defendant sold a house without telling them that the house's previous inhabitants had been brutally murdered 10 years earlier.
There are a number of other metaphors and expressions which refer to small changes leading to chains of events with undesirable or unexpected consequences, differing in nuances.
- Foot in the door - a persuasion technique
- Slippery slope - an argument, sometimes fallacious
- "The thin end of the wedge"
- Domino effect
- For Want of a Nail - the claim that large consequences may follow from inattention to small details
- Boiling frog
- "Give them an inch; they'll take a mile." The original saying goes "Give them an inch, and they'll take an ell."
- In Chinese culture, the "inch-mile" saying corresponds to the expression 得陇望蜀 (De long wang shu), which is a quotation from the Book of Later Han about a Chinese general who took over Long (now Gansu) only to pursue further southwards into Shu (now Sichuan).
- In Russian culture a similar phrase sounds, literally translated, as "offer him a finger, and he will bite a hand off up to the elbow".
- In Finnish, there is the expression Jos antaa pirulle pikkusormen, se vie koko käden ("If you offer the devil [even just] a little finger, it takes the whole hand/arm").
- Wilson, John T. (1983). Academic Science, Higher Education, and the Federal Government, 1950-1983. University of Chicago Press. p. 51.
- Quoted in Pierce, Patrick Alan; Miller, Donald E. (2004). Gambling Politics: State Government and the Business of Betting. Lynne Rienner Publishers. p. 133. Retrieved 2007-09-15.
- Nunberg, Geoffrey (2005). Going Nucular: Language, Politics and Culture in Controversial Times. New York: PublicAffairs. p. 118. ISBN 978-1-58648-345-6. Retrieved July 9, 2011.
- Anonymous (1858). "Sin is a Bad Master". The Child's Companion and Juvenile Instructor. The Religious Tract Society. p. 14.
- Sigourney, Lydia Huntley (1860). "An Arab Fable". Gleanings. D. Appleton. pp. 58–59. Retrieved 2007-09-15.
- The New York Times, April 21, 1875
- The New York Times, March 14, 1878.
- West, John. "Multiplicity of Reports". Retrieved 20 April 2015.
- Horace Scudder. The Book of Fables and Folk Stories (originally published in 1915) Yesterday's Classics (2006) ISBN 1-59915-127-8
- "Cambridge International Dictionary of Idioms", Cambridge University Press (1998)
- "Give them an inch...", a China Daily column, July 6, 2006