If you ever saw that picture of Emmett Till, you never forgot it.

Not the one that shows a handsome brown teenager, hat tipped up slightly off his forehead. Not, in other words, the before picture.

No, I’m talking about the picture that was taken after. After he went down from Chicago to visit family in Mississippi in the late summer of 1955. After he accepted a schoolboy dare to flirt with a white woman working behind the counter of the general store. After he called her “baby,” and allegedly gave a wolf whistle. After her husband and his half brother came for him in the dead of night. After his body was fished from the Tallahatchie River.

The picture of him that was taken, published in Jet magazine and flashed around the world, was stomach-turning. A lively, prankish boy had become a bloated grotesquerie, an ear missing, an eye gouged out, a bullet hole in his head. You looked at that picture and you felt that here was the reason coffins have lids.

But his mother refused onlookers that mercy, refused to give him a closed-casket funeral. She delayed the burial for four days, keeping her son’s mutilated body on display as thousands came to pay their respects. “I wanted the world to see what I had seen,” she later explained. “I wanted the world to see what had happened in Mississippi. I wanted the world to see what had happened in America.”

The world saw and was electrified.

Mamie Till Mobley died in Chicago on Monday, apparently of a heart attack. And if one were seeking to sum up her life, it might be enough to say that she spent 47 years keeping the casket open, speaking, writing and agitating in the name of her murdered son. Indeed, her book “The Death of Innocence” is due for release later this year.

I met her once, maybe 30 years after her son’s death, by which point she must have told his story a million times. And she still welled up as she spoke, her voice stammering and turning gray.

At the time, I was writing and producing a radio documentary tracing more than 500 years of black history. I’ll never forget my narrator’s response when he reviewed a script that recounted Emmett’s ordeal and the ordeals of other black men and women who were hanged, burned and hacked to pieces for the crime of being. He jokingly dubbed me “the Stephen King of black history” for my insistence on including the grisly details.

But I happen to believe Mamie Till Mobley was right to keep the casket open.

We’re always so eager to hide the horror. Close the casket, turn your eyes, use euphemism to obscure truths too obscene.

Consider Trent Lott’s first attempt at apology, when he blithely described segregation as “the discarded policies of the past.” If you didn’t know any better, you might have thought he was talking about farm subsidies or tax code, so bloodless and opaque was the language.

But segregation wasn’t opaque and it surely wasn’t bloodless. It was a Mississippi courtroom where the sheriff sauntered in every day and greeted spectators in the colored section with a cheery, “Hello, niggers.” It was two white men freely admitting that they had kidnapped a black Chicago boy. It was witnesses who placed the men at a barn inside which they heard a child being tortured. And it was a jury of white men who heard this evidence, then deliberated for less than an hour before returning an acquittal.

As one of them told a reporter, “If we hadn’t stopped to drink pop, it wouldn’t have took that long.”

This is the fetid truth behind the flowery words, the stinking fact much of the nation would prefer not to know.

But by her very presence, a murdered boy’s mother demanded that we be better than that, demanded that we be, at least and at last, brave enough to face the horrors we have made and that have, in turn, made us.

Mamie Till Mobley was 81 years old at the time of her death. Her only child was 14 at the time of his.