Professor Mabel Newcomer (1892-1983) told her Vassar freshman class in September 1935: “You are the generation about to come into control and must prepare for this responsibility. Do not fill uo your leisure with meaningless activity or with causes. have the courage to stand aside and watch for a little while. It is more important to know where we are going than to get there quickly. Do not mistake activity for achievement.”
   
“Do not mistake activity for achivement” (or “Never mistake activity for achievement”) was frequently reprinted in periodicals, often with her last name misspelled as “Newcomber.”
 
Similar sayings have been cited in print from 1919 and 1931. Basketball coach John Wooden has often used the phrase.
 
   
Vassar Encyclopedia
Mabel Newcomer
Mabel Newcomer taught in the Vassar economics department from 1917 to 1957. An outstanding educator, she combines her excellent teaching and faculty leadership with her activities as a professional economist. She was known as the best “tax man” of those years. Her students’ Vassar experience was vastly enriched.
 
The daughter of one of Stanford University’s first professors of English, Miss Newcomer earned both her bachelor’s and master’s degrees in economics at that university (1913 and 1914 respectively). Her thesis on the California experiment in permitting local governments to use the property tax was sent with her application for graduate work to a number of universities. Columbia University offered her the largest fellowship and for her doctoral dissertation she expanded her thesis to include all states which had turned over the property tax to the local government.
 
Her Columbia professors gave her the original contacts to state and federal agencies and commissions with whom she would do research for decades and gave her the part time teaching job at Barnard where the chairman of the Vassar economics department (Herbert Mills) observed her in the winter of 1916-17. Miss Newcomer became the fifth member of Vassar’s economics department in 1917. By 1926 she was a full professor.
     
Google Books
The Gillette Blade
v. 2, nos. 3-14
1919
Pg. 4:
There are too many people who mistake activity for achievement; and not enough importance is given to the use of human brains.
 
8 May 1931, New Castle (PA) News, “Brown Grist” by Mrs. Thad C. Brown, pg. 17, col. 1: 
“The trouble seems to be that many women are prone to confuse activity with achievement.”
 
24 September 1935, New York (NY) Times, pg. 21:
FRESHMEN WARNED
OF HASTY DECISIONS
Prof. Newcomer Tells Vas-
sar Girls to “Observe” Before
“Jumping to Conclusions.”
HITS GERMANY AS EXAMPLE
She Asserts “Feverish Activity”
There Has Gained Nothing—
Academic Honors Awarded.
POUGHKEEPSIE, N. Y., Sept. 23.—Professor Mabel Newcomer of the Economic Department at Vassar College greeted the freshman class today with a warning to go slowly and observe for a time before jumping to conclusions.
 
Returned from a year in England and Germany, Professor Newcomer reiterated her faith in the democratic form of government.
 
“I am convinced that democracy need not be bungling and can be made to work, but this demands the highest level of intelligence and education,” she said. “You are the generation about to come into control and must prepare for this responsibility. Do not fill uo your leisure with meaningless activity or with causes. have the courage to stand aside and watch for a little while. It is more important to know where we are going than to get there quickly. Do not mistake activity for achievement.”
 
28 September 1935, New York (NY) Times, “Topics of The Times,” pg. 14:
The Swift Gesture.
Vassar freshmen were told by Professor MABEL NEWCOMER to go slow in passing judgment on things. She told them not to mistake activity for achievement, and to remember that it is more important to know where one is going than to get there quickly. All this has a classic ring, not to say old-fashioned, and it is therefore surprising to learn that the advice is based on very fresh data, Professor NEWCOMER, whose field is economics, is just back from Germany. She found the country given over to speed and restlessness, without real planning for the future. One political leader told her that in Germany they cannot see beyond today.
 
Yet there are other leaders in Germany who cannot be accused of lacking a goal or hitting up too fast a tempo. They are the men whose estimates of the time it will take to carry out the complete Nazification of the German people run from 500 years to 1,000 years. Surely that cannot be called precipitate.
 
Google Books
Psychology Applied
By George Washington Crane
Chicago, IL: Hopkins Syndicate
1950
Pg. 311:
“It is more important to know where you are going than to get there quickly. Do not mistake activity for achievement.”—Mabel Newcomber
 
Google News Archive
14 September 1951, Toledo (OH) Blade, “Wisdom for Today,” pg. 29, col. 1:
It is more important to know where you are going than to get there quickly. Do not mistake activity for achievement.
—Prof. Mabel Newcomber.
 
Google Books
They Call Me Coach
By John R Wooden with Jack Tobin
Chicago, IL: Contemporary Books
2004
Pg. 82:
Possibly a frequent comment of mine describes the difference. “Don’t mistake activity for achievement.”
   
Google Books
The Forbes Book of Business Quotations:
10,000 Thoughts on the Business of Life
By Ted Goodman
New York, NY: Black Dog & Leventhal Publishers
2006
Pg. 20:
It is more important to know where you are going than to get there quickly. Do not mistake activity for achievement.
MABEL NEWCOMBER