“How long? Not long, because the arc of the moral universe is long, but it bends toward justice.”

King's often repeated expression that "The arc of the moral universe is long, but it bends towards justice" was his own succinct summation of sentiments echoing those of Theodore Parker, who, in "Of Justice and the Conscience" (1853) asserted: "I do not pretend to understand the moral universe; the arc is a long one, my eye reaches but little ways; I cannot calculate the curve and complete the figure by the experience of sight; I can divine it by conscience. And from what I see I am sure it bends towards justice."
1960s, Where Do We Go from Here: Chaos or Community? (1967)
Context: I must confess, my friends, the road ahead will not always be smooth. There will be still rocky places of frustration and meandering points of bewilderment. There will be inevitable setbacks here and there. There will be those moments when the buoyancy of hope will be transformed into the fatigue of despair. Our dreams will sometimes be shattered and our ethereal hopes blasted. We may again with tear-drenched eyes have to stand before the bier of some courageous civil rights worker whose life will be snuffed out by the dastardly acts of bloodthirsty mobs. Difficult and painful as it is, we must walk on in the days ahead with an audacious faith in the future. … When our days become dreary with low-hovering clouds of despair, and when our nights become darker than a thousand midnights, let us remember that there is a creative force in this universe, working to pull down the gigantic mountains of evil, a power that is able to make a way out of no way and transform dark yesterdays into bright tomorrows. Let us realize the arc of the moral universe is long but it bends toward justice.

2013, "Let Freedom Ring" Ceremony (August 2013)
Context: To dismiss the magnitude of this progress -- to suggest, as some sometimes do, that little has changed -- that dishonors the courage and the sacrifice of those who paid the price to march in those years. Medgar Evers, James Chaney, Andrew Goodman, Michael Schwerner, Martin Luther King Jr. -- they did not die in vain. Their victory was great. But we would dishonor those heroes as well to suggest that the work of this nation is somehow complete. The arc of the moral universe may bend towards justice, but it doesn’t bend on its own. To secure the gains this country has made requires constant vigilance, not complacency. Whether by challenging those who erect new barriers to the vote, or ensuring that the scales of justice work equally for all, and the criminal justice system is not simply a pipeline from underfunded schools to overcrowded jails, it requires vigilance. And we'll suffer the occasional setback. But we will win these fights. This country has changed too much. People of goodwill, regardless of party, are too plentiful for those with ill will to change history’s currents.

2018, Nelson Mandela Annual Lecture (2018)
Context: It was in service of this long walk towards freedom and justice and equal opportunity that Nelson Mandela devoted his life. At the outset, his struggle was particular to this place, to his homeland – a fight to end apartheid, a fight to ensure lasting political and social and economic equality for its disenfranchised non-white citizens. But through his sacrifice and unwavering leadership and, perhaps most of all, through his moral example, Mandela and the movement he led would come to signify something larger. He came to embody the universal aspirations of dispossessed people all around the world, their hopes for a better life, the possibility of a moral transformation in the conduct of human affairs.
Madiba’s light shone so brightly, even from that narrow Robben Island cell, that in the late ‘70s he could inspire a young college student on the other side of the world to reexamine his own priorities, could make me consider the small role I might play in bending the arc of the world towards justice. And when later, as a law student, I witnessed Madiba emerge from prison, just a few months, you’ll recall, after the fall of the Berlin Wall, I felt the same wave of hope that washed through hearts all around the world.
Do you remember that feeling? It seemed as if the forces of progress were on the march, that they were inexorable. Each step he took, you felt this is the moment when the old structures of violence and repression and ancient hatreds that had so long stunted people’s lives and confined the human spirit – that all that was crumbling before our eyes. And then, as Madiba guided this nation through negotiation painstakingly, reconciliation, its first fair and free elections; as we all witnessed the grace and the generosity with which he embraced former enemies, the wisdom for him to step away from power once he felt his job was complete, we understood that – we understood it was not just the subjugated, the oppressed who were being freed from the shackles of the past. The subjugator was being offered a gift, being given a chance to see in a new way, being given a chance to participate in the work of building a better world.

How long? Not long, because "you shall reap what you sow."
1960s, How Long, Not Long (1965)

2011, Remarks on Egyptian political transition (February 2011)
Context: I know that a democratic Egypt can advance its role of responsible leadership not only in the region but around the world.
Egypt has played a pivotal role in human history for over 6,000 years.  But over the last few weeks, the wheel of history turned at a blinding pace as the Egyptian people demanded their universal rights.
We saw mothers and fathers carrying their children on their shoulders to show them what true freedom might look like.
We saw a young Egyptian say, “For the first time in my life, I really count.  My voice is heard.  Even though I’m only one person, this is the way real democracy works.”
We saw protesters chant “Selmiyya, selmiyya” — “We are peaceful” — again and again.
We saw a military that would not fire bullets at the people they were sworn to protect.
And we saw doctors and nurses rushing into the streets to care for those who were wounded, volunteers checking protesters to ensure that they were unarmed.
We saw people of faith praying together and chanting – “Muslims, Christians, We are one.”  And though we know that the strains between faiths still divide too many in this world and no single event will close that chasm immediately, these scenes remind us that we need not be defined by our differences.  We can be defined by the common humanity that we share.
And above all, we saw a new generation emerge — a generation that uses their own creativity and talent and technology to call for a government that represented their hopes and not their fears; a government that is responsive to their boundless aspirations.  One Egyptian put it simply:  Most people have discovered in the last few days…that they are worth something, and this cannot be taken away from them anymore, ever.
This is the power of human dignity, and it can never be denied. Egyptians have inspired us, and they’ve done so by putting the lie to the idea that justice is best gained through violence.  For in Egypt, it was the moral force of nonviolence — not terrorism, not mindless killing — but nonviolence, moral force that bent the arc of history toward justice once more.

"Three-legged Dog", The Golden Hour (May 6, 2008).
Lyrics, Firewater

El Perú es desde este momento libre e independiente por la voluntad general de los pueblos y por la justicia de su causa que Dios defiende. ¡Viva la patria! ¡Viva la libertad! ¡Viva la independencia!
(Declaration of the Peruvian independence, July 28, 1821).

1 St. Tr. (N. S.) 382.
Trial of Hunt and others (King v. Hunt) (1820)

Six Principles of Political Realism, § 5.
Politics Among Nations (1948)
Context: Political realism refuses to identify the moral aspirations of a particular nation with the moral laws that govern the universe. As it distinguishes between truth and opinion, so it distinguishes between truth and idolatry. All nations are tempted — and few have been able to resist the power for long — to clothe their own aspirations and action in the moral purposes of the universe. To know that nations are subject to the moral law is one thing, while to pretend to know with certainty what is good and evil in the relations among nations is quite another. There is a world of difference between the belief that all nations stand under the judgment of God, inscrutable to the human mind, and the blasphemous conviction that God is always on one's side and that what one wills oneself cannot fail to be willed by God also.