I remember reading a work of fiction where someone made a comment
about people who laugh by themselves are simply pretending to be in
the company of others.  The character in the novel was actually
quoting another source.

I'd be happy with the original source of the quote, but I'm
specifically looking for the work of fiction that had a character
quote it.

Hi metallicplastic,

The quote you remember is:

"Anyone who laughs alone is imagining the company of others."

The origin of this quote is from the book Le Rire by French
philosopher and Nobel Prize Laureate, Henri Bergson.


The only reference I found to this quote in another novel is in the
book Saint Augustine by Gary Willis, where Augustine uses this quote
as described below:

"In his exhaustive search for some conceivable good to be found in his
bad act, Augustine finally comes up with a psychological clue:
Whatever his motive for acting with the gang, he would not have done
the same thing all by himself. Does that suggest some good hidden in
the bad? He finds a psychological parallel that may help him toward an
explanation. People normally laugh when together, not when alone?or,
as Bergson put it, anyone who laughs alone is imagining the company of
others (Le Rire 1). There is something essentially social about
laughter. Companionship (consortium) is the good in the morally
indifferent act of laughing..."

Google Print: Saint Augustine
http://print.google.com/print/doc?isbn=0670886106


Search criteria:
people laugh "by themselves" pretending
"* who laugh "by themselves" pretending "company of others"
"* who laugh "by themselves" "company of others"
"* who laugh" "company of others"
"* who laugh" "pretending to be" company others
"who laugh" pretending "to be in" company others
"* who laugh alone" pretend company others
"* who laughs alone" 
 bergson "laugh alone"


I hope the information provided is helpful. 

Best regards,
Rainbow-ga

Ah, excellent!  Saint Augustine is exactly where I remembered it from.
 Thanks also for the clarification of the quote.

Hi metallicplastic,
I'm glad I was able to help. Thank you for the rating and tip.
Best regards,
Rainbow~