“To the world you may be just one person, but to one person you may be the world”

“To the world you may be just one person, but to one person you may be the world” is a saying that has been printed on many posters. “To the world you may be one person, but to one person you may be the world” has been cited in print since at least 1998.
 
“Brandi Snyder, writer” is credited in some of the later citations. Authorship of the saying remains unknown.
 
   
Google Groups: alt.music.dave-matthews
An Open Letter to the Newsgroup- from Greedom1
DMBDeadfan
10/12/98
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“To the world you may be one person, but to one person you may be the world.”
 
Google Groups: alt.fan.dragons
[PSI] Definitions (everyone involved with [PSI], please read!
Orion
4/11/99
(...)
“To the world you may be one person, but to one person you may be the world.” ~anonymous
 
9 May 2000, The Daily Globe (Ironwood, MI), “Tidbits,” pg. 3, col. 1:
Another gem from our Internet friends, a piece entitled “The 14 Things to Live By,” a list with a decidedly distaff feel. So ladies, enjoy.
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8. To the world you may be one person, but to one person you may be the world.
     
Google Books
Still the One:
Keeping the Love, Keeping the Laughter
By Martha Bolton
Grand Rapids, MI: Fleming H. Revell
2001
Pg. 81:
To the world you may be just one person, but to one person you may be the world.
Source unknown
 
Google Books
1,600 Quotes & Pieces of Wisdom That Just Might Help You Out When You’re Stuck in a Moment (and can’t get out of it!)
By Gary Guthrie
Lincoln, NE: iUniverse, Inc.
2003
Pg. 36:
To the world you may be one person, but to one person you may be the world.—Author unknown
 
Google Books
Mom Candy:
1,000 Quotes of Inspiration for Mothers
Edited by Jena Pincott
New York, NY: Random House
2013
Pg. 80:
To the world you may be just one person, but to one person you may be the world. —Brandi Snyder, writer