“I always have a quotation for everything—it saves original thinking” was written by English crime novelist Dorothy L. Sayers (1893-1957) in Strong Poison: Have His Carcase (1932). The quote, not surprisingly, has made many collections of quotations.
 
   
Wikipedia: Dorothy L. Sayers
Dorothy Leigh Sayers (usually pronounced /ˈseɪ.ərz/, although Sayers herself preferred /ˈsɛərz/ and encouraged the use of her middle initial to facilitate this pronunciation; 13 June 1893 – 17 December 1957) was a renowned English crime writer, poet, playwright, essayist, translator, and Christian humanist. She was also a student of classical and modern languages.
 
She is best known for her mysteries, a series of novels and short stories set between the First and Second World Wars that feature English aristocrat and amateur sleuth Lord Peter Wimsey, which remain popular to this day
 
Google Books
Lord Peter and Harriet. Part I,
Strong Poison:
Have His Carcase
By Dorothy L. Sayers
Garden City, NY: Mystery Guild
1932, 1930
Pg. 323:
“‘Blossoms of the honey- sweet and honey-colored menuphar’ — I always have a quotation for everything — it saves original thinking.”
   
Google Books
The Oxford Dictionary of Quotations
By Elizabeth M. Knowles
Oxford: Oxford University Press
1999
Pg. 646:
Dorothy L. Sayers 1893-1957
English writer of detective fiction
I always have a quotation for everything — it saves original thinking.
Have His Carcase (1932)
 
Google Books
Women Know Everything!:
3,241 Quips, Quotes, & Brilliant Remarks
By Karen Weekes
San Francisco, CA: Chronicle Books
2007
Pg. 341:
I always have a quotation for everything — it saves original thinking.
DOROTHY L> SAYERS (1893-1957) - ENGLISH WRITER AND TRANSLATOR
 
Google Books
The Biteback Dictionary of Humorous Literary Quotations
By Fred Metcalf
London: Biteback Publishing Ltd.
2013
Pg. ?:
I always have a quotation for everything—it saves original thinking.
Dorothy L. Sayers, Have His Carcase (1932)
 
Twitter
Steve B
‏@SDB57
“I always have a quotation for everything—it saves original thinking.” (Lord Peter Wimsey)
Dorothy.L.Sayers
#quotes
3:40 AM - 20 Oct 2015