It is an enduring mystery of life how the moral range of humanity can stretch from a twisted young racist such as Dylann Roof, who faces charges of slaughtering six women and three men during a Bible-study class, to a woman such as Nadine Collier, who is the daughter of one of the victims, Ethel Lance, and who was able to find it in her heart to turn to Roof at his bond hearing and say, “I forgive you.”

How many of us are capable of that? Imagine the capacity for grace in Felicia Sanders, who lost her son, Tywanza, in the Emanuel A.M.E. Church massacre, and who said to the alleged killer at the hearing, “Every fibre in my body hurts, and I will never be the same. But as we say in Bible study, we enjoyed you. But may God have mercy on you.” We enjoyed you. This is a superhuman form of endurance and pity. The world is such a fallen place that it is somehow easier to comprehend the deranged cruelty of Dylann Roof than the unfathomable and uncompromising mercy of Nadine Collier and Felicia Sanders.

And yet this is an old story. To study the history of the black freedom movement is to be astonished by its collective capacity for forbearance. The litany of its great leaders—Frederick Douglass, Martin Luther King, Jr., Malcolm X, and Fannie Lou Hamer among them—is vastly outnumbered by the anonymous millions who encountered the noose, the lash, the cattle prod, the attack dog, the laws of Jim Crow, and answered it all, so often, in the spirit reflected by the survivors and the congregation at the Emanuel African Methodist Episcopal Church. Those soldiers of the movement were clear-eyed about their oppressors. They were the least naïve people imaginable and they were hardly weak. But they answered most often not to the understandable urge to vengeance but to the call of a preternaturally elevated form of justice and mercy. Within the black freedom movement, there was always a debate about the tension between nonviolent resistance and the need for resistance and rebellion, between the tactics and rhetoric of Martin Luther King, Jr., and Malcolm X, between the Southern Christian Leadership Conference and the Black Power movement. But to know the history is to be at once awed and unsurprised by women like Nadine Collier and Felicia Sanders.

Dylann Roof does not stand at the head of a movement. He did not enter Emanuel A.M.E. Church with a mob trailing behind him. He is a loner, a solitary fanatic. But he derives his hatreds and obsessions from a history of American racism and a still-existing cultural seedbed of white supremacism. On Saturday, some persistent amateur investigators on Twitter uncovered what appears to be Roof’s Web site. It is called lastrhodesian.com. [link] The F.B.I. and other law-enforcement agencies have not yet authenticated the site’s grotesque manifesto or its cache of sixty photographs. But both the 2,444-word-long text (“An Explanation”) and the photographs echo in spirit the on-the-record testimonies of acquaintances and family members who have described, to reporters in South Carolina, Roof’s recent turn to racist statements and behavior.

The manifesto reflects a stark and twisted obsession with minorities and race, particularly African-Americans but also Jews and Hispanics. It is drenched in white-separatist racial solidarity; mordant self-pity; and conspiracy thinking. The text moves from blunt hatred (“Niggers are stupid and violent”) to a kind of lunatic auto-didacticism: “In a modern history class it is always emphasized that, when talking about ‘bad’ things Whites have done in history, they were White. But when we lern about the numerous, almost countless wonderful things Whites have done, it is never pointed out that these people were White. Yet when we learn about anything important done by a black person in history, it is always pointed out repeatedly that they were black. For example when we learn about how George Washington carver was the first nigger smart enough to open a peanut.” (I’ve left all of the grammatical and spelling mistakes uncorrected. It seems the least one could do.)

The anti-Semitism in the text is such that it is a wonder the killer did not make a stop at a local synagogue on the way to Emanuel A.M.E. Church with his .45-calibre handgun. (“Just like niggers, most jews are always thinking about the fact that they are jewish. The other issue is that they network. If we could somehow turn every jew blue for 24 hours, I think there would be a mass awakening, because people would be able to see plainly what is going on.”)

Roof’s photographs appear to show his interest in the racially resonant landscapes of his state. There are pictures of a local plantation; the Museum and Library of Confederate History, in Greenville; and a Confederate cemetery. He shows himself both trampling and burning the Stars and Stripes. (“I hate the sight of the American flag.”) But he displays the Confederate flag with a look of enormous self-regard. In some pictures, he displays the numerals 1488 and 88, a set of code numbers well known in white-supremacist circles. The number 14 stands for a fourteen-word separatist slogan: “We must secure the existence of our people and a future for White Children.” George Lincoln Rockwell, the founder of the American Nazi Party, used 88 as a code for “HH”—“Heil Hitler.” “H” is the eighth letter of the alphabet.

In one picture, Roof wears a now infamous jacket (with patches of both the apartheid-era South African flag and the Rhodesian flag) while standing next to a plaque marking where he is: Sullivan’s Island, off the coast of Charleston. Sullivan’s Island is where, in the early eighteenth century, four hundred thousand men, women, and children arrived from West Africa to be sold into bondage. Historians estimate that around forty per cent of the enslaved Africans brought to British North America arrived at Sullivan’s Island. In 2008, Toni Morrison led three hundred people in a ceremony on the island commemorating the history of slavery in America. We can safely assume that Roof visited the island in a far different spirit.

“The Last Rhodesian” starts out his text by saying that he was not raised in a “racist home or environment.” But an event from three years ago altered his mood.

“The event that truly awakened me was the Trayvon Martin case,” he writes. “I read the Wikipedia article and right away I was unable to understand what the big deal was. It was obvious that Zimmerman was in the right. But more importantly this prompted me to type in the words ‘black on White crime’ into Google, and I have never been the same since that day. The first website I came to was the Council of Conservative Citizens. There were pages upon pages of these brutal black on White murders. I was in disbelief. At this moment I realized that something was very wrong. How could the news be blowing up the Trayvon Martin case while hundreds of these black on White murders got ignored?”

The Council of Conservative Citizens is, according to the Southern Poverty Law Center, a modern incarnation of a notorious pro-segregation group of the nineteen-fifties and sixties, the White Citizens Councils. The C.C.C.’s Web site calls African-Americans “a retrograde species of humanity,” and it has published caricatures of Michael Jackson as an ape. Its newspaper has encouraged whites to vacation in South Carolina in order to “enjoy a civil liberty that has been denied to them for many years at hotels, restaurants and beaches: the freedom to associate with just one’s own people.” The C.C.C. has tried to position itself as more respectable than the Ku Klux Klan. The late Supreme Court Justice Thurgood Marshall called the C.C.C. “the uptown Klan.”