“There’s always a certain number of suckers and a certain number of men lookin’ for a chance to take them in, and the suckers are sure to be took one way or another. It’s the everlastin’ law of demand and supply. p. 60”

on working in Hollywood
Reported by musician Michael Feinstein, transcript of * Fresh Air Celebrates Frank Loesser's 100th Birthday
http://www.npr.org/2010/06/29/128169934/fresh-air-celebrates-frank-loesser-s-100th-birthday
Fresh Air
http://www.npr.org/programs/fresh-air/
Host: Terry Gross, Guest: Michael Feinstein
NPR
WHYY
Philadelphia
2009-06-29
2:34
http://www.npr.org/templates/transcript/transcript.php?storyId=128169934

Philosophical Essay on Probabilities (1902)
Context: The theory of chance consists in reducing all the events of the same kind to a certain number of cases equally possible, that is to say, to such as we may be equally undecided about in regard to their existence, and in determining the number of cases favorable to the event whose probability is sought.<!--p.6

Source: Salem Falls

Comment prior to the "Rumble in the Jungle" about George Foreman prior to the fight, when referee Clayton warned Ali that if he didn't stop talking he would stop the fight. (30 October 1974)

Alaska Young, p. 113
Looking for Alaska (2005)

Source: Reminiscences of a Stock Operator (1923), Chapter IX, p. 103

Source: The Diviners

it would be deemed snobbish to investigate only the best people
“Clinical and Cultural Aspects of the Aging Process,” p. 485
Individualism Reconsidered (1954)

Commonly attributed to Barnum, there is much testimony of contemporaries that he never actually said this, and in "P. T. Barnum Never Did Say "There's a Sucker Born Every Minute" http://www.historybuff.com/library/refbarnum.html R. J. Brown asserts that it actually originated with a banker named David Hannum, in reference to one of Barnum's hoaxes: a replica of the Cardiff Giant.
Misattributed