The arc of the moral universe is long, but it bends towards justice.

Martin Luther 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." [from Wikipedia]