That rug quote nontroversy is pathetic. There are two different quotes:

“The arc of the moral universe is long, but it bends toward justice.” — Martin Luther King

“I do not pretend to understand the moral universe; the arc is a long one… . But from what I see I am sure it bends toward justice.” — Theodore Parker

MLK’s may very well have been inspired by Parker. However, it is clear that the exact quote, “The arc of the moral universe is long, but it bends toward justice” is not attributable to Parker but King.