The Youth’s Companion (a popular American children’s magazine) published this anonymous line in 1891: “Either as wife, sister, husband or brother, if you would have a happy family life, remember two rules. In matters of principle stand like a rock. In matters of taste swim with the current.”
 
There is no evidence that Thomas Jefferson (1743-1826) ever said it, although Jefferson was being given credit for it by 1972. The word “taste” was replaced by “style” in the 1980s: “In matters of style, swim with the current; in matters of principle, stand like a rock.”
 
 
Wikiquote: Leadership
In matters of style, swim with the current; In matters of principle, stand like a rock.
Thomas Jefferson
   
Wikipedia: Thomas Jefferson
Thomas Jefferson (April 13, 1743 – July 4, 1826) was the third President of the United States (1801–1809), the principal author of the Declaration of Independence (1776), and one of the most influential Founding Fathers for his promotion of the ideals of republicanism in the United States. Jefferson envisioned America as the force behind a great “Empire of Liberty” that would promote republicanism and counter the imperialism of the British Empire.
   
1 January 1891, New York (NY) Times, “Gossipy Gleanings,” pg. 2:
REMARKS the Youth’s Companion:
 
Either as wife, sister, husband or brother, if you would have a happy family life, remember two rules. In matters of principle stand like a rock. In matters of taste swim with the current.
 
25 January 1891, Syracuse (NY) Herald, pg. 6, col. 6:
Two Rules.
Youth’s Companion.
Either as wife, sister, husband or brother, if you would have a happy family life, remember two rules:
 
In matters of principle stand like a rock.
In matters of taste swim with the current.
 
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More Borrowings
Compiled by Ladies of the First Unitarian Church of Oakland, California
San Francisco, CA: Charles Albert Murdock & Co., printers
1891
Pg. 39:
“If you would have a happy family life, remember two things, — in matters of principle, stand like a rock; in matters of taste, swim with the current.”
 
Google Books
The Texas Women’s Hall of Fame
By Sinclair Moreland
Austin, TX: Biographical Press
1917
Pg. 147:
“If you would have a happy family life, remember two things,—in matters of principle, stand like a rock; in matters of taste, swim with the current.
   
30 October 1972, Lubbock (TX) Avalanche-Journal, “In New York With Earl Wilson,” pg. 16C, col. 7:
REMEMBERED QUOTE: “In matters of principle, stand like a rock. In matters of taste, swim with the current.”—Thomas Jefferson.
 
Google News Archive
20 April 1973, Nevada (MO) Daily Mail, pg. 4, col. 2:
Gough quotes Thomas Jefferson as saying, “In matters of principle, stand like a rock; in matters of taste, swim with the current.”
   
Google Books 
Working Woman
v. 14 - 1989
Pg. 104:
As Thomas Jefferson said, “In matters of style, swim with the current; in matters of principle, stand like a rock.”
   
Google Books
Phillips’ book of great thoughts, funny sayings:
A stupendous collection of quotes, quips, epigrams, witticisms, and humorous comments : for personal enjoyment and ready reference
By Bob Phillips
Wheaton, IL: Tyndale House
1993
Pg. 62:
In matters of style, swim with the current; in matters of principle, stand like a rock. Thomas Jefferson
   
23 June 1993, Milwaukee (WI) Journal Sentinel, “Great thinkers offer thoughts for dad”:
Thomas Jefferson: “In matters of style, swim with the current. In matters of principle, stand like a rock.”
(From “A Father’s Book of Wisdom”—ed.)
   
Springfield (MO) News-Leader
Missouri laws still fail state government whistleblowers
Scott Eckersley • January 25, 2010
“In matters of style, swim with the current; in matters of principle stand like a rock. All tyranny needs to gain a foothold is for people of good conscience to remain silent.”
—Thomas Jefferson
My former boss, Matt Blunt, insisted on Thomas Jefferson quotes in his speeches; I’m not sure if he ever used this one, but I doubt it. Nevertheless, it’s a quote I grew to love because of what it connotes about the importance of government whistleblowers and the laws that they protect.