“A cluttered up desk is the sign of a cluttered up mind” has been cited in print since at least 1947. “If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” is a jocular saying that has been printed on many gift items. Cited in 1954 was, “He comments that, ‘A cluttered desk is a sign of a cluttered mind.’ He never bothers to say what an empty desk is a sign of.” “If a cluttered desk is a sign of a cluttered mind, we can’t help wondering what an empty desk indicates” was cited in print in 1955.
   
The physicist Albert Einstein (1879-1955) has been credited with the saying in the 2000s, but there’s no evidence that he said it. It’s possible that the brilliant mind of Einstein attached to the saying of a cluttered/empty mind has made the saying more popular.
 
“Tidy desk, tidy mind” has been cited in print since about 1948, “Tidy room, tidy mind” since 1982 and “Tidy house, tidy mind” since 1986.
 
   
Google News Archive
24 April 1947, Kentucky New Era (Hopkinsville, KY), “‘Mares’ Nest’ Desk Explained” by Hal Boyle, pg. 8, col. 3:
Each club member will keep a coconut in his desk drawer—if there is room. It will be used to bash each and every office wayfarer who comes by and says:
 
“A cluttered up desk is the sign of a cluttered up mind.”
 
For this machine-age proverb is one of the major falsehoods of the industrial world with its watchword—efficiency.
 
I think it is more likely that “a clean desk is the sign of a fearful mind.” When people are worried, nervous or afraid, they have to do things with their hands. So they tidy their desk with busy fingers and put all their paper problems into folders and hid them away.
 
Google Books
Marriage:
A Discovery Together
By John G. Quesnell
Notre Dame, IN: Fides Publishers
1954
Pg. 70:
He comments that, “A cluttered desk is a sign of a cluttered mind.” He never bothers to say what an empty desk is a sign of.
 
4 April 1955, Chicago (IL) Tribune, :Good Morning” by The Wildrooter, pg. A3:
If a cluttered desk is a sign of a cluttered mind, we can’t help wondering what an empty desk indicates.
 
30 June 1955, Elgin (IA) Echo, pg. 8, col. 7 ad:
If a cluttered desk is a sign of a cluttered mind, we can’t help wondering what an empty desk indicates.
(Schori & Kuster—ed.)
 
Google News Archive
21 September 1959, Ottawa (Ontario) Citizen, “Today’s Laugh Lines” by Alex, pg. 16, col. 8 ad:
If a cluttered desk is the sign of a cluttered mind, we can’t help wondering what an empty desk indicates.
(Alexandra Hotel—ed.)
 
Google Books
Humorous English;
A guide to comic usage, jocular speech and writing, and witty grammar
By Evan Esar
New York, NY: Horizon Press
1961
Pg, 246:
If a cluttered desk is the sign of a cluttered mind, what is the significance of an empty desk?
   
New York (NY) Times
Scanner Cuts Desktop Paper Clutter
By STEPHEN WILLIAMS
Published: May 7, 2009
Albert Einstein said, ‘‘If a cluttered desk signs a cluttered mind, of what, then, is an empty desk a sign?’’
 
No offense to Professor Einstein, but an overgrown mess decorating my desk makes me anxious. That’s why NeatDesk for Mac is a breath of feng shui in my house.
 
Twitter
Erin Iles‏
@erin_iles  
“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?”  ― Albert Einstein.
1:51 PM - 6 Sep 13