“And finally, rising inequality and declining mobility are bad for our democracy. Ordinary folks can’t write massive campaign checks or hire high-priced lobbyists and lawyers to secure policies that tilt the playing field in their favor at everyone else’s expense. And so people get the bad taste that the system is rigged, and that increases cynicism and polarization, and it decreases the political participation that is a requisite part of our system of self-government.”

2013, Remarks on Economic Mobility (December 2013)
Context: So let me repeat: The combined trends of increased inequality and decreasing mobility pose a fundamental threat to the American Dream, our way of life, and what we stand for around the globe. And it is not simply a moral claim that I’m making here. There are practical consequences to rising inequality and reduced mobility. For one thing, these trends are bad for our economy. One study finds that growth is more fragile and recessions are more frequent in countries with greater inequality. And that makes sense. When families have less to spend, that means businesses have fewer customers, and households rack up greater mortgage and credit card debt; meanwhile, concentrated wealth at the top is less likely to result in the kind of broadly based consumer spending that drives our economy, and together with lax regulation, may contribute to risky speculative bubbles.

The ‘Bad’ Parts of Technology Cannot Be Separated From the ‘Good’ Parts, paragraph 121
Industrial Society and Its Future (1995)

Dissenting, Obergefell v. Hodges, 135 S. Ct. 2584, 192 L. Ed. 2d 609 (2015) ; decided June 26, 2015.
2010s

1964 Memorial Edition, p. 265 http://www.jfklibrary.org/Research/Research-Aids/Ready-Reference/JFK-Quotations/Profiles-in-Courage-quotations.aspx
Pre-1960, Profiles in Courage (1956)

2015, Remarks to the United Nations General Assembly (September 2015)
Context: I understand democracy is frustrating. Democracy in the United States is certainly imperfect. At times, it can even be dysfunctional. But democracy -- the constant struggle to extend rights to more of our people, to give more people a voice -- is what allowed us to become the most powerful nation in the world. It's not simply a matter of principle; it's not an abstraction. Democracy -- inclusive democracy -- makes countries stronger. When opposition parties can seek power peacefully through the ballot, a country draws upon new ideas.  When a free media can inform the public, corruption and abuse are exposed and can be rooted out. When civil society thrives, communities can solve problems that governments cannot necessarily solve alone. When immigrants are welcomed, countries are more productive and more vibrant. When girls can go to school, and get a job, and pursue unlimited opportunity, that’s when a country realizes its full potential. […] And I believe that what is true for America is true for virtually all mature democracies.  And that is no accident. We can be proud of our nations without defining ourselves in opposition to some other group. We can be patriotic without demonizing someone else. We can cherish our own identities -- our religion, our ethnicity, our traditions -- without putting others down. Our systems are premised on the notion that absolute power will corrupt, but that people -- ordinary people -- are fundamentally good; that they value family and friendship, faith and the dignity of hard work; and that with appropriate checks and balances, governments can reflect this goodness.

The Semisovereign People (1960)

Source: A Confederacy of Dunces (1980, posthumous), Ch. 2, opening line

in Public Choice Ignorance Everywhere http://athousandnations.com/2010/11/09/public-choice-ignorance-everywhere/, November 2010

1990s, Our March to Freedom is Irreversible (1990)