When, at Mamie Till’s insistence, the coffin was opened, she saw her son’s right eyeball sitting on his cheek, dangling by the optic nerve. Let that single grisly detail stand in for all the rest. Let it speak to the savagery two white men unleashed upon the body of a 14-year-old black boy named Emmett Till.

On Saturday, a new marker was dedicated at the Tallahatchie River in Mississippi, from which his body was fished in August 1955. This is the fourth such memorial to Till, a Chicago boy who was kidnapped, tortured and murdered for supposedly getting fresh with a white woman at a local store.

The first marker wasn’t installed until 2008. It disappeared. The next two were shot full of holes. The new one is said to be bulletproof, with protective glass and reinforced steel. It weighs 500 pounds and will reportedly be monitored by video cameras transmitting to the internet.

Even so, one wonders how long it will last. Where race is concerned, after all, white resistance to memory is often mulish. Black resistance too, sometimes. As Jessie Jaynes-Diming, a member of the Emmett Till Memorial Commission, recently told NPR, “Whites and blacks came to our meetings and (said), ‘Why are you all bringing this up? Why don’t y’all let that die?’ ”

John Whitten would agree. A former county prosecutor, he was 7 years old when his namesake father defended the killers in court. Till, he told NPR, “came down here and got in trouble – overstepped his bounds to a degree some folks thought. And they cured him of his problems. I think all these folks are stirring crap up. Every day, somebody’s dragging up the race card. Somebody saying we have racial disparity here. If nobody would stir that damn pile of stuff up, it wouldn’t stink.”

It is, yes, a crude and atavistic assessment. But, though others would likely use more oblique language, Whitten speaks the hearts of many white people when he says these are things we shouldn’t “stir.” For example, he speaks for Newt Gingrich who, in August, denounced a New York Times project on the history of slavery as “a lie.” And for the Alabama nurse who complained last year to Britain’s Guardian newspaper that a new lynching memorial is “just stirring up something.”

If some African Americans resist these stories because of the pain, many whites resist them because of the stain – the smudge on self-image, the blot on conscience, the blemish on the mythology of white virtue and innocence. They feel indicted by memory, so they try to kill it. “It’s hard not to be embarrassed,” a then-20-year-old white guy named Ryan Price told me in 2011. We had just sat through a documentary, “The Murder of Emmett Till.”

In watching the movie, he said, “You get to the point where you almost want to change your skin color so you can show how much you care about issues of race, how much you care about the overt hatred and vitriolic discrimination of the past and today. Of course, you can’t change your skin color, but you can be an ally to those who are marginalized in society, and that’s something it really spurs me to do.”

That young man’s words inspired me – not only his willingness to grapple honestly with his feelings, but his determination to use those feelings for good. If more of us had courage like his, a simple commemorative sign would not have to be bulletproof or weigh 500 pounds. And history would not be a threat but, as he puts it, a spur. Unfortunately, too many of us have not courage, but cowardice.

They seek to murder memory. But you see, memory fights back.

So maybe they should make peace with it instead.

Leonard Pitts Jr. is a columnist for The Miami Herald. He can be contacted at:

lpitts@miamiherald.com