Which is why I believe that the long arc of the moral universe is a actually more like an evolving scavenger hunt. A few people with an evolved morality and a keen conscience recognize an injustice, whether inflicted upon themselves or others, embedded in the norm of their society. These are the ones who find the cause, start the movement and bring the light, and over time the norm shifts and the law changes, and even those lagging behind the ethical curve are dragged along, kicking and screaming.
I believe the arc of the moral universe will continue bending slowly through time, past one discovered and discarded injustice at a time. And what more valuable gold could we find at the end than the words, "Do unto others as you would have them do unto you".