When Samuel Huntington wrote The Clash of Civilizations, he presaged the Boston Marathon bombings by the proposition that the cause of future conflict will no longer be economic or territorial; rather, our woes will come from profound differences in culture.  If nothing else, the emerging profile of the Tsarnaev brothers strongly suggests that our society simply does not understand the implacable forces that shape people who, with ball caps and backpacks, can kill with dedication, resolve, and reason.

In the United States, as David Ortiz explained, we imagine Americans as a committed part of a national unity.  Our ethnic origins become heritage, our languages cohabit with English, our colors, often slow to succumb, eventually are blended into the physical evidence of a powerful mosaic.  We pride ourselves in what Ortiz said at Fenway, but the most telling words from Tamerlan Tsarnaev was that he did not "understand Americans" and had "no American friends."  Remarkably, during a time when creating enough virtual friends to fill Fenway is the social obsession, Tamerlan lived outside while he lived within.  If he was a loner who traveled back to be trained in the black arts, he joins a long list of the disaffected.

It is in the story of younger brother, Dzhokhar, that the true mystery resides.  He came at to America at eight years old, and all of his adolescence was American-honed.  He was just another high school kid, evidently liked, fully into teen mantras of sport, proms, and pot.  He was not indifferent to his social world or, like many politically motivated teenagers, a champion for a visible cause.  His politically active peers learned to make posters and online surveys while he learned to make bombs.

A month ago, Newtown children were killed by a young man with evident mental illness.  This fact shaped the national dialogue as to whether it was access to guns or lack of access to mental health care that drove that tragedy.  In the litany of sage Boston commentaries, there is no presumption that mental illness, much less psychotic ideation, drove these brothers not only to violence, but to something even darker: the planting of explosives designed to dismember and maim.  The Tsarnaevs' bombs loaded with shrapnel were kind if they killed.

In much of the world, and especially in non-Western lands, the ties that bind derive from family, clan, tribe, region, and, often, an integrating religion.  Any memory of a nation-state is often recalled as an imposition of imperial or colonial origin.  Chechnya has an abundant history of a vital national and religious homogeneous identity.  To hear the brothers' uncle is to hear Chechen national pride and its centuries-long tradition of a Sunni Islam adherence to a revered and scholarly Sufi jurisprudence.  Yet at the margins of its modern history reside jihad.

Jihad, to Sunnis means "struggle," in two forms: "lesser" and "greater."  In their reading of the Koran, Sunnis' greater struggle is the internal obligation to fulfill religious duties, but the "lesser" is to fight the enemies of Islam.  There is, in fact, an actual choice one can make among jihads: of the heart, of the tongue with words, of the hands with righteous actions, and of the sword.

Kurtz, in Apocalypse Now, recalled how the Viet Cong had returned to a village in which the American Special Forces had vaccinated the children against polio.  The Cong hacked off each inoculated arm, and Kurtz wept at the "genius of that" -- of the Viet Cong showing that they were capable of seeing moral terror, meaning the horror of unspeakable acts, as a friend unto itself.  They were "genuine, complete, crystalline, and pure."  This is what the brothers strove to be. It should impress us as much as it did Kurtz.

It hardly matters if the older brother swayed the younger.  The latter was transformed by far more than filial esteem.  He went to the dorm and gym on the Wednesday after he blew limbs off scores of people.  He met his friends after killing both savagely and with indifference.  He ran over his brother as he hurled pipe bombs and hand grenades.  He needed to be subdued with concussive grenades even when nearly mortally wounded.  He had become a soldier of the type that Kurtz longed for.  He was, within his own motives and rationale, heroic.  To the others watching CNN many miles and centuries away, he will be romantically remembered and imitated.

We celebrated at Fenway for good reason and then played baseball.  In the recent book, 500 Days, Kurt Eichenwald details the compelling fear, in the days after 9/11, that more destructive mass attacks were imminent.  In this context, the president conceived of a global war on terror that engaged both participants and passively supporting groups or nations.  This doctrine led us to Iraq in the belief that it had the potential, in weapons and in the political leadership, to join or support terror.  It led to the moral ambiguities of the CIA drone programs; the astonishing extent, as just witnessed, of the capacity to photograph and analyze citizens; and, Law and Order episodes aside, to a little-known exception to providing Miranda rights to the arrested.

Let me pose this second act.  The brother recovers enough to admit that there is another cell and that they are planning a mass public killing.  He demands his Miranda rights (or his attorney surely will) and refuses to tell what he knows in revenge for the death of his brother.  He says that what will happen will make the Marathon bombing look childish and that that bombing was strategically done to flesh out the limitations of surveillance and police response.

I cannot imagine the consequences if Fenway were indefinitely closed or the nation felt itself captive -- not just regionally, but from sea to shining sea.  Our sensitivity to harsh interrogation, or surveillance, or "stop and frisk" would be sorely tested, as would the future of any politician who did not do a pretty good George Bush imitation.

What we have seen in the last few days is as prescient as Huntington's essay in 1993.  There are thousands of young people bred to the bone and absolutely committed to causes that make a joke of Red Sox or Yankee ardor.  We cannot see them, even when among us, for we cannot imagine that Facebook, the wresting team, the prom, the fast food, the good humor, the Hunger Games, the America that has Talent or Dancers or Idols is not a guarantee of love and loyalty.  But it is not.