light a fire under
light a fire under (idiom / metaphor)
/ˈlaɪt ə ˈfaɪər ˌʌndər/
Meanings
- To motivate someone to act quickly or with energy.
- To pressure someone into taking action.
- To inspire or push someone toward achieving a goal.
- (Literal) To actually start a fire beneath something.
Synonyms: motivate; push; encourage; energize; inspire; provoke.
Example Sentences
- The coach had to light a fire under the team after their poor first-half performance.
- The manager’s speech really lit a fire under the employees to finish the project on time.
- Her mentor managed to light a fire under her to pursue her dream career.
- They used wood to light a fire under the pot to start cooking. (literal)
Origin and History
The idiom “light a fire under (someone)” means to urge or motivate someone to act more quickly or energetically. The metaphor evokes fire as a symbol of stimulus or energy, applied “under” someone to prompt movement.
The Chimney-Sweep Hypothesis
A popular theory attributes the idiom to a cruel practice in 18th- and 19th-century Europe, particularly Britain, where chimney-sweep masters allegedly lit small fires beneath flues to force hesitant apprentice “climbing boys” to work faster. This story, often cited in non-scholarly sources and histories of chimney-sweeping, provides vivid imagery but lacks direct evidence linking it to the idiom’s origin.
Evaluation of Theories
- Chimney-Sweep Hypothesis (Plausible but Unsubstantiated) Historical accounts confirm that fires were used to coerce chimney-sweep apprentices, lending plausibility to the imagery. However, no direct documentary evidence ties this practice to the idiom’s origin. The story’s prominence in popular sources suggests it may be a folk etymology.
- Metaphorical Development in English (Most Likely) Fire has long symbolized energy or motivation in English (e.g., “kindle enthusiasm,” “fire someone’s zeal”). The shift from literal fire to figurative motivation is a natural semantic extension.
Country of Origin
the idiom’s origin in the United States. While the chimney-sweep practice was European (especially British), the phrase’s documented development in American English suggests it crystallized there.
Earliest Printed Records
The idiom “light a fire under (someone)” emerged in literary contexts, with early printed records showing variations in wording. The earliest figurative use appears in Mark Twain’s The Adventures of Tom Sawyer (1876), published in London by Chatto & Windus on 9 June 1876 and in Hartford by the American Publishing Company on 8 December 1876:
“The boy could not have shown a wilder, heartier interest, if she had built a fire under him.”
The modern phrasing, “light a fire under (him)”, appears later in P. G. Wodehouse’s “The Fatal Kink in Algernon” (Ladies’ Home Journal, January 1916):
“…the only way to get Algie to do anything except to eat was to light a fire under him and leave the rest to nature.”
By the late 1890s to early 1900s, the idiom was common in American English, indicating its widespread use around the turn of the 20th century.
Variants
- light a fire under someone
- put a fire under someone
- get a fire under someone
- set a fire under someone
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