Source: Trent's Own Case (1936), Chapter XV: "Eunice Makes a Clean Breast of It"
“Don't confine yourself to a select group of friends, often known as a clique. Cliques by definition leave people out. Lock yourself into one, and you'll never know how many terrific friendships you may be missing.”
Source: Today I Will: A Year of Quotes, Notes, and Promises to Myself
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Jerry Spinelli 67
American children's writer 1941Related quotes

“If you make friends with yourself, you'll never be alone.”
Variant: If you make friends with yourself you will never be alone.
Quotes from him, Csillag születik (talent show between 2011-2012)

Oration in Defense of Flaccus. See Apostle Paul: A Polite Bribe https://books.google.com.br/books?id=wefkDwAAQBAJ&pg=108 by Robert Orlando, p. 108.

Source: This is All: The Pillow Book of Cordelia Kenn

Mister Rogers' Neighborhood: Thoughts For All Ages http://pbskids.org/rogers/all_ages/thoughts1.htm