The quote portrays a truth of humanity that we, as humans, don't like to admit to. People are not always going to be able to prevent injustice - we won't always see abuse or crime, we don't always notice inequality, unfairness and prejudice won't always be preventable, and we have to admit to that. If people see an injustice, we must not "fail to protest." Protesting may be in the littlest forms, like refusing to join in with bullying or something bigger, like marching in a woman's march to prove your point. Protest is necessary to stopping injustice where we may not be able to otherwise. Not everyone can fly around in a cape like superman but we can protest injustice when we feel powerless.
