A man purported to be Islamic State captive Muath al-Kasaesbeh, a Jordanian pilot, stands in front of armed men in this still image that was filmed at an undisclosed location and made availab on social media Tuesday. (Reuters Tv/Reuters)

Perhaps it doesn’t matter if you look. The latest atrocity from the Islamic State, the immolation of a captured Jordanian pilot, caught on camera and distributed to an almost universally horrified planet, will do its basic work regardless of whether anyone watches it. This is about triggering the imagination, compelling us to think and see the world through an iron-age filter. There is no subtle message, perhaps no message at all, in its horrific cruelty. Its purpose is simply to make us more tribal.

As with so much of the ugliness perpetrated by the Islamic State, what’s old is new. Read Dabiq, the slick online magazine published by the Islamic State, and you’ll encounter a strange, temporal whiplash. It is a catalogue of atavistic brutalities and yet strangely unimaginative in its celebration of violence. This isn’t about mankind’s macabre ability to invent new forms of murder; it’s about reanimating our oldest, and collectively shared, habits of barbarism. When we learn that they have stoned an adulterer to death, or pushed a homosexual man off a high wall, we may wonder, “What will they think of next?” But the Islamic State is not innovative in its depredations. Its thugs simply reach into the museum of human-made misery and pull out something at once horribly familiar, and terribly alien.

This is certainly true of its use of beheading. Walk through any great gallery of old master paintings and beheading will seem as ordinary as the gold frames and marble floors. Perseus holds the head of Medusa; Judith saws through the neck of Holofernes; Salome leers lasciviously at the face of John the Baptist; David displays his trophy from the fallen Goliath. Beheading is a shared tradition, a cross-cultural possession. The French practiced it until 1977, when the guillotine fell for the last time on the neck of a Tunisian immigrant charged with rape and murder.

We may have banished beheading as an acceptable form of execution in the West, but we still live with the historical and iconographic remains of its widespread use. And yet artistic images of bloody heads and gore-soaked swords never feel quite real, and don’t inspire much horror anymore. They are safely sewn up in a legendary past, disconnected from our own seemingly civilized present. The Islamic State wants to erase that distance, not just to horrify us, but to drag us back with them. The goal may be more ambitious than merely outraging the moral sensibilities of the world, or proving its own bottomless reserves of destructive will. Rather, the Islamic State wants to reconnect us to our own not-so-distant past, when we were more than capable of similar acts of savagery.

Beheading is a particular case. The United States still uses execution as an instrument of state power, but we have for the most part moved to clinical, medicalized forms of judicial killing. Beheading, as practiced by the Islamic State, is intimate, hands-on, manual death. If you haven’t the stomach to watch video of any of the many beheadings to emerge from Syria and Iraq in the past few years, then look up Rembrandt’s 1635 “The Sacrifice of Isaac,” held by the Hermitage in St. Petersburg. Beheading looks a lot like this excruciating image of divinely sanctioned death: One body is bound and defenseless, the other straining to the task, grasping and pulling at the head and face of another living being as if it were an animal. But of course in the real-life beheadings, there is no angel to intervene, the knife never falls out of the executioner’s hand and the grisly work proceeds to completion in under a minute.

The Islamic State has effectively reacquainted us with the pure physicality of killing, bypassing our carefully constructed defenses — media protocols, government euphemism — that have kept the effects of war and torture at a discreet and safe distance. Merely the thought of a man being burned alive overwhelms our best efforts to edit savagery out of the imaginable world.

If the violence of the Islamic State often feels disconcertingly Old Testament, that’s no accident. By reenacting the appalling excesses of what we would call biblical violence in the modern world, it has issued us an invitation, a chance to return to what it posits as the basic moral condition governing all men. It is a family reunion of sorts, a chance to relive the fratricides and infantacides and genocides that give our shared religious narratives their bloody vigor, a chance to live together under the most blunt and unimaginative law ever promulgated: An eye for an eye.

With the recent killings of two Japanese hostages and the burning alive of Lt. Muath al-Kaseasbeh, there are reports that the Islamic State is running out of hostages or, at least, running low on foreign hostages whose deaths would galvanize world reaction. Have they miscalculated? Have they failed to leverage any advantage? Have they simply turned the world against them? But those may be irrelevant questions. These killings have already done much of what they were likely meant to do. They have reset the clock, rekindled tribal thinking and, worst of all, implanted visceral ideas about what a satisfying revenge would look like.