I know you are asking today, "How long will it take?...How long will justice be crucified, and truth bear it?" ... How long? Not long, because the arc of the moral universe is long, but it bends toward justice.
-- Martin Luther King, Jr., Address at the Conclusion of the Selma to Montgomery March, 25 March 1965
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. But from what I see I am sure it bends towards justice.
-- Theodore Parker, "Of Justice and the Conscience", 1853