Rock musician Frank Zappa (1940-1993) said in a February 1971 interview (available on YouTube):

“Well I think that progress is not possible without deviation. And I think that it’s important that people be aware of some of the creative ways in which some of their fellow men are deviating from the norm, because in some instances they might find these deviations inspiring and might suggest further deviations which might cause progress, you never know.”
 
In a 1987 book, this quote was shortened to, “My attitude toward anybody’s sexual persuasion is this: without deviation from the norm, progress is not possible.” The quote is usually presented as, “Without deviation from the norm, progress is not possible.”
 
   
Wikipedia: Frank Zappa
Frank Vincent Zappa (December 21, 1940 – December 4, 1993) was an American musician, composer, guitarist, recording engineer, record producer, and film director. In a career spanning more than 30 years, Zappa composed rock, jazz, orchestral and musique concrète works. He also directed feature-length films and music videos, and designed album covers. Zappa produced almost all of the more than 60 albums he released with the band The Mothers of Invention and as a solo artist.
 
Information Is Not Knowledge
Frank Zappa (VPRO-TV February 1971)
(...)
40:49 Progress
FZ:
Well I think that progress is not possible without deviation. And I think that it’s important that people be aware of some of the creative ways in which some of their fellow men are deviating from the norm, because in some instances they might find these deviations inspiring and might suggest further deviations which might cause progress, you never know.
 
Google Books
The Gay Book of Lists
By Leigh W. Rutledge
Boston, MA: Alyson Publications
1987
Pg. 200:
FRANK ZAPPA, U.S. musician “My attitude toward anybody’s sexual persuasion is this: without deviation from the norm, progress is not possible.”
     
Google Books
20 June 1994, New York magazine, pg. 47:
1966
My attitude toward anybody’s sexual persuasion is this: without deviation from the norm, progress is not possible.
FRANK ZAPPA
 
Google Books
Sing Out!:
Gays and Lesbians in the Music World
By Boze Hadleigh
New York, NY: Barricade Books
1997
Pg. 32:
He (Frank Zappa—ed.) later led the anti-crusade vs. the Washington Wives who wanted to censor rock lyrics, particularly gay ones, and asserted, “My attitude towards anybody’s sexual persuasion is: without deviation from the norm, progress is not possible.”
 
14 July 2000, Aberdeen (SD) American News, Farm Forum, pg. 63F, col. 1 ad:
“Without deviation from the norm, progress is not possible.” (Frank Zappa)
(Aberdeen Livestock Sales Co.—ed.)
 
YouTube
Without deviation from the norm, Progress is not possible
Roy
Uploaded on Dec 3, 2011
Frank Zappa
(“I think that progress is not possible without deviation. And I think that it’s important that people be aware of some of the creative ways in which some of their fellow men are deviating from the norm. Because in some instances they might find these deviations inspiring and might suggest further deviations which might cause progress. You never know.”—ed.)