“Never mistake the enthusiasm of the minority for the support of the majority.”

Transcript: The Breitbart Geert Wilders Interview http://www.breitbart.com/london/2015/06/19/transcript-the-breitbart-geert-wilders-interview/ by Oliver JJ Lane, breitbart.com (19 June 2015)
2010s

1960s, Where Do We Go from Here: Chaos or Community? (1967)
Context: Nowhere have the riots won any concrete improvement such as have the organized protest demonstrations. When one tries to pin down advocates of violence as to what acts would be effective, the answers are blatantly illogical. Sometimes they talk of overthrowing racist state and local governments and they talk about guerrilla warfare. They fail to see that no internal revolution has ever succeeded in overthrowing a government by violence unless the government had already lost the allegiance and effective control of its armed forces. Anyone in his right mind knows that this will not happen in the United States. Furthermore, few, if any, violent revolutions have been successful unless the violent minority had the sympathy and support of the non-resisting majority.

Statement (26 June 1787) as quoted in Notes of the Secret Debates of the Federal Convention of 1787 http://avalon.law.yale.edu/18th_century/yates.asp by Robert Yates
1780s
Context: The man who is possessed of wealth, who lolls on his sofa or rolls in his carriage, cannot judge the wants or feelings of the day-laborer. The government we mean to erect is intended to last for ages. The landed interest, at present, is prevalent; but in process of time, when we approximate to the states and kingdoms of Europe, — when the number of landholders shall be comparatively small, through the various means of trade and manufactures, will not the landed interest be overbalanced in future elections, and unless wisely provided against, what will become of your government? In England, at this day, if elections were open to all classes of people, the property of landed proprietors would be insecure. An agrarian law would soon take place. If these observations be just, our government ought to secure the permanent interests of the country against innovation. Landholders ought to have a share in the government, to support these invaluable interests, and to balance and check the other. They ought to be so constituted as to protect the minority of the opulent against the majority. The senate, therefore, ought to be this body; and to answer these purposes, they ought to have permanency and stability.

1850s, Lecture at Brooklyn (1859)

Interview with Claudia Dreifus in September and October 1995, published in Times Magazine (4 February 1996)

Source: Thoughts in the Cloister and the Crowd. 1901, p.17.

Speech before the Federal Club http://www.theodore-roosevelt.com/images/research/txtspeeches/581.pdf, New York City, (6 March 1891), as published in New York Daily Tribune (7 March 1891)
1890s
Context: Of recent years... representative government all over the world has been threatened with a growing paralysis. Legislative bodies have tended more and more to become wholly inefficient for the purposes of legislation. The prime feature in causing this unhealthy growth has been the discovery by minorities that under the old rules of parliamentary procedure they could put a complete stop to all legislative action... If the minority is as powerful as the majority there is no use of having political contests at all, for there is no use in having a majority.

Attributed to Twain, but never sourced. Suspiciously close to "A minority may be right, and the majority is always in the wrong." — Henrik Ibsen "Enemy of the People," as well as a famous quote from Danish philosopher Søren Kierkegaard
Misattributed