“All of us can be influenced through psychological techniques. For example, if I say “don’t think of a black cat” what do you do? You think of a black cat because the command ‘think of a black cat’ was there in the sentence. Techniques like this can be used to influence people’s thoughts, behaviour, even their memory.”
TV Series and Specials (Includes DVDs), Mind Control (1999–2000) or Inside Your Mind on DVD
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Derren Brown136
British illusionist 1971Related quotes
“The hardest thing of all is to find a black cat in a dark room, especially if there is no cat.”
Confucius (-551–-479 BC) Chinese teacher, editor, politician, and philosopher
Eliezer Yudkowsky Harry Potter and the Methods of Rationality
Harry Potter in Ch. 2 http://www.hpmor.com/chapter/2 <br class="br">Harry Potter and the Methods of Rationality (2010 - 2015)

Oscar Wilde (1854–1900) Irish writer and poet
This quote was instead first mentioned in a 1931 book titled “Since Calvary: An Interpretation of Christian History” by the comparative religion specialist Lewis Browne.
Disputed
“Like searching at midnight in a dark cellar for a black cat that isn’t there.”
Robert A. Heinlein book Starman Jones
Source: Starman Jones (1953), Chapter 11, “Through the Cargo Hatch” (p. 115)
Tommy Douglas (1904–1986) Scottish-born Canadian politician
So they put him in jail. But I want to remind you: that you can lock up a mouse or a man but you can't lock up an idea!
http://www.cbc.ca/player/Digital+Archives/Politics/Parties+and+Leaders/Tommy+Douglas/ID/1409090169/?sort=MostPopular
Vincent Van Gogh (1853–1890) Dutch post-Impressionist painter (1853-1890)
Quote in his letter to brother Theo, from Nuenen, The Netherlands, Autumn 1885; as quoted in Vincent van Gogh, edited by Alfred H. Barr; Museum of Modern Art, New York, 1935 https://www.moma.org/documents/moma_catalogue_1996_300061887.pdf, (letter 428) p. 31 <br class="br">1880s, 1885