Now that teasers have begun to emerge for the upcoming X-Files revival—eight seconds of footage, followed by the revealed return of the Lone Gunmen, and an epic marathon of the show’s existing episodes on Fox—it’s the perfect time to consider what made that show so good in the first place. Much is made of the aliens and black goo, the corn fields and aura of pervasive conspiracy. But none of that really accounts for the show’s enduring resonance, its ability to burrow under the skin and stay there.

One answer comes early, in the third episode of the first season, titled “Squeeze.” Perhaps the best episode of the show’s nine seasons, “Squeeze” tells the story of Eugene Victor Tooms, a serial killer capable of contorting his body through the narrowest of spaces, who eats the livers of his victims, and hibernates for years in nests made of newspaper strips congealed with his own bile. This alone is pretty grim stuff, obviously, but the strength of “Squeeze” comes from its ability to make the familiar unfamiliar. The gap beneath a door becomes a source of dread; a slow-zoom on an air vent is rendered almost intolerable. Like all episodes of The X-Files that really prickle and creep, “Squeeze” is a masterpiece of the uncanny.

As The New Yorker’s Emily Nussbaum recently identified, the uncanny has come to feature in a surprisingly broad range of contemporary television shows. On Fox’s Wayward Pines, which debuted in May, a Secret Service agent finds himself trapped inside a small Idaho town where time skews unstably, and where the inhabitants appear to be only acting normal. In the BBC’s Orphan Black, a young woman literally doubles and triples as a clone, then assumes the identity of one of her doppelgängers. In FX’s American Horror Story, lampshades are made of human skin, and a freak show circus (what could be more unsettling than clowns?) distorts joy into grotesque horror.

The trend can also be seen in streaming shows: The dead reappear in The Returned, upending the proper course of nature; and a deceased lover is replaced with a mechanical simulacrum in an episode of Black Mirror. Even procedural dramas are suffused with weirdness: In The Fall, a mannequin is used to evoke the ghostly shape of the killer Paul Spector’s victims. Tugging out a common thread, Nussbaum labeled these shows as living and dying “by their devotion to that old Freudian concept of ‘the uncanny.’”

Sigmund Freud wrote his essay on the subject in 1919, and the intervening century has done little to diminish its fascination. The uncanny “undoubtably belongs to all that is terrible,” Freud writes, but it is categorically unique “within the boundaries of what is ‘fearful.’” Freud invokes the ambiguous German word heimlich to describe exactly what sets the uncanny apart: “On the one hand, it means that which is familiar and congenial, and on the other, that which is concealed and kept out of sight.” He offers a dizzying array of examples: wax-work figures, artificial dolls, and automatons; doubles “in every shape and degree,” including faces, crimes, or oddly recurring names. “When one wanders about in a dark, strange room, looking for the door or the electric switch, and collides for the hundredth time with the same piece of furniture”—that is uncanny. When somebody seems to possess inexplicable powers, or something is freighted with an excess of symbolic weight, like “a hand cut off at the wrist”—also uncanny. “To many people the idea of being buried alive while appearing to be dead is the most uncanny thing of all,” he concludes.

In a visual medium like television, the uncanny can work in several different ways. It can be channeled through ambient mood—the desaturated Louisiana seen in season one of True Detective, where Rust Cohle describes one location as “like somebody's memory of the town, and the memory’s fading.” It can also come in violent riffs that tear the surrounding fabric of normalcy. The uncanny is that moment in Mad Men when the camera lingers too long on a banal office party, until a secretary, riding a lawnmower around the desks, mangles a man’s foot, showering her colleagues with blood. (That there can be humor in the uncanny is a fact that many British television comedians have made their forte, from Matthew Holness to The League of Gentlemen.)

The master of uncanny television remains David Lynch, whose incomparable Twin Peaks is slated to return to Showtime in 2017. As with The X-Files, cult nostalgia has tended to emphasize the ostentatious elements of the original series to explain its appeal, like the mysterious Red Room with its dancing dwarf. But the uncanniness, which gave the series heft, was due to Lynch’s expert use of allusions, alternate realities, and the suggestion of other meanings hidden just below the surface of the town. Twin Peaks took a familiar genre and made it foreign. Traffic lights and wind accrued ominous subtext. The local busybody became a log-carrying savant, whispering, “The owls are not what they seem.” Even the idea of guilt in a murder investigation—who, exactly, killed Laura Palmer?—became hopelessly opaque. In a climactic scene of such brutal strangeness that it still has the ability to stun, Laura’s father, Leland Palmer, snaps on plastic gloves and then murders his niece Maddie in a warmly lit living room. Or does he? During a slow-motion assault, he becomes superimposed identities, both himself and not himself, Leland and the evil spirit BOB, present and absent, human and ghost, lost somewhere in-between.

Twin Peaks has often been said to have a dreamlike texture for its ability to interweave fears and desire. But there’s a big difference between the genuinely uncanny—that which connects with something profound, something deep within ourselves—and the more crudely fantastical, which relies on non-sequiturs and surrealism to cheat the same effect.

A contemporary example is Hannibal, which aspires to channel the uncanny in every episode. The first two seasons, largely set in a looking-glass Maryland or Minnesota, fizzle with scenes that feel projected straight from the collective unconscious. Grain silos, deer antlers, and totem poles shed their comfortable “meanings” to assume new, irregular ones that render the world disorientating. In this shadow America, a person can become a beehive, a violin, a mushroom farm—even dinner. Indeed, those dishes served by Dr. Lecter, as beautiful as paintings by Jan Davidsz. de Heem, looks appetizing even as you understand they probably contain human flesh. A viewer is both attracted and repulsed, a perfect storm of opposing emotions that makes the first two seasons of Hannibal the most vertigo-inducing television show since—well, Twin Peaks or The X-Files.

By comparison, the first half of the third season, which temporarily relocates the action to a vague, unconvincing Italy, dispenses with the police procedural frame, the therapy sessions, and lonely farmsteads. The result is unmoored, even flaccid: A man strung up as a firefly with wings of shattered glass has no connection to reality, and therefore can’t distort it, creating that uncanny torque. Hannibal in Baltimore is savage and unsettling; it has something interesting to say about our appetite for violence. Hannibal in Florence is a meaningless Grand-Guignol.

All of this raises an important question: Why are viewers so compelled by the weird and inexplicable? Why the increasing glut of uncanny television shows that try to take the world and turn it upside down? Why the clamor to see dead classics resurrected for a second life?

Freud, unsurprisingly, looks to the unconscious for an explanation of the uncanny, writing that the invention of doubling, for example, “has its counterpart in the language of dreams, which is fond of representing castration by a doubling or multiplication of the genital symbol.” (Genitals and the castration complex: responsible for everything). But I’m more persuaded by the author Jeff VanderMeer, who describes weird fiction as a cathartic way “to seek out and tell stories that do not seek to reconcile the illogical, the contradictory, and often instinctual way in which human beings perceive the world, but instead accentuate these elements as a way of showing us as we truly are.”

Watching this sort of television, I’m reminded that I live with an outlook that is stiflingly rigid, that culture and science have armed me with an intolerance towards open-ended questions and ambiguity. Faced with the weirdness of existence, I seek laws, explanations; everything set in its rightful place. The uncanny rejects this. It subverts the idea of order, then dilates the world with unfathomable mystery. This is unnerving—the uncanny is scary—but it can also be compelling, even a comfort. Because maybe we are only seeing part of the whole, the uncanny suggests, holding out a lure of greater enlightenment. “I believe that what we’re looking for is in the X-Files,” Fox Mulder tells Dana Scully. “I’m more certain than ever that the truth is in there.”