Editor’s note, May 23, 2020: Today marks the 10th anniversary of the series finale of Lost. Here’s what we wrote about the show’s best installment in 2018 when we named it the best TV episode of the 21st century.

In a now-famous sequence, a camera starts with a bird's-eye view of half of Jack Shephard’s (Matthew Fox) face as he lies in a jungle. He opens one eye, the camera pans out, he gets up, and he runs onto a beach, where he finds the wreckage of a plane from whence he came. The ensuing scene is loud and violent. Survivors are screaming. Michael Dawson (Harold Perrineau) yelps his first “Waaaalllttttt!” of the series as he looks for his son. Then the chaos subsides, and the castaways transition into survival mode. Lost began with a boom on September 22, 2004, on ABC. At the time, the pilot looked like a dramatic, worst-case-scenario, $14 million rendering of Survivor (which was hugely popular in 2004, with roughly 20 million viewers each week). The ABC drama was immediately galvanizing, as the J.J. Abrams–and–Damon Lindelof–led two-hour series premiere was more movie than TV episode.

It’s an iconic pilot that astonishes on every rewatch, but within the context of Lost, it’s an anomaly. The flashbacks show only the recent history of the flight before the plane crashed. Kate Austen (Evangeline Lilly) immediately catches Jack’s attention, but there are only hints of love triangles. Scary sounds and amorphous movements and a polar bear come from the jungle, but the true terrors that plagued the survivors of Oceanic 815 don’t materialize until later on in the show. If a new viewer watched just the pilot, she would think it was a science-fiction show about survival on an island with supernatural qualities—The Twilight Zone meets Cast Away.

The 100 Best TV Episodes of the Century Check out The Ringer’s ranking of the best episodes since 2000

The debt owed to The Twilight Zone is undeniable, but ultimately Lost was a unique, paradigm-shifting show that had influences but few forebears. The pilot, like many others, is a misleading token of the show. It announced Lost as something important and ambitious, but it does not capture the series at its most singular. When a group of Ringer staffers sat down to compile a list of the best episodes of TV since the year 2000, we attempted to identify episodes across genres that affected television at large while also encapsulating what made a given TV show special. That’s how we arrived at “The Constant,” the fifth episode of Season 4, which first aired on February 28, 2008.

“The Constant” doubles as a mission statement for the show. Desmond Hume (Henry Ian Cusick), the guy who entered the numbers and lived in the hatch, becomes the vessel by which Lost explains its rules for time travel and emphasizes the primacy of pathos. With assists from Sayid Jarrah (Naveen Andrews) and Daniel Faraday (Jeremy Davies), Desmond struggles to stop his mind from jumping between two timelines. The key to stabilizing him is making contact with his love, Penny Widmore (Sonya Walger), a connection that fans had been pining for.

The episode exemplifies what gave Lost broad appeal: It weaves together classic science-fiction tropes and melodramatic relationships. “The Constant” was particularly special because it quietly redefined the narrative techniques that the show relied on. The episode doesn’t contain flashbacks, but rather it follows Desmond’s consciousness as it jumps between Britain in 1996 and a freighter off the coast of the island in 2004. The hard cuts between locales belie the linear narrative Desmond experiences in the installment. It’s set up to look like a regular episode, wherein a small portion of the ensemble cast advance the mystery related to the island—namely, what is it, who knows about it, and who are the people on it?—while (usually) one character is the subject of a series of flashbacks that illuminate his or her actions on the island. “The Constant” slightly alters this formula by having Desmond discover the nature of his reality—one in which his mind jumps across drastic time gaps—along with the viewers.

Depending on who’s watching the episode, the practicalities of time travel are secondary to the more emotional plot. The episode’s crescendo builds toward a moving, brief phone call between Penny and Des. Like every character worth remembering on Lost, Penny has myriad connections to the crew on the island, the crew on the freighter, and one of the primary villains of the show. But this episode is a Lost miracle because, for 43 minutes (without commercials), Penny’s backstory beyond her breakup with Desmond is irrelevant. So is most of his. What matters is that they love each other, and she is his grounding force—his constant. Ultimately they speak via satellite phone on this much-discussed sea vessel, and it produces the single most emotional scene from a show that trafficked in sentimentality.

Partial credit is owed to Cusick and Walger that a large swath of fans cared deeply about the love story of two characters who were ancillary to the original premise. But this moment packed so much force because it capped an episode that managed to service both factions of its audience equally. For viewers who invested in the myriad romantic relationships, the phone call represented a type of emotional payoff that Lost rarely delivered. The hard-core fans invested in the science-fiction story lines and attendant logic (or lack thereof) received a cogent explanation about how time travel works. It was a question that had loomed since Desmond’s clairvoyance came to light in Season 2, but with Faraday as narrator, we finally understood how Desmond could intermittently see the future. Time travel laws became a major point of contention in Season 5 when the device was more central to the story, but after “The Constant,” several articles pointed out that what Desmond experienced was not entirely impossible, if still highly implausible.

If a latecomer or a millennial wanted to understand why Lost mattered enough to make millions of fans irate after a disappointing finale, “The Constant” would be the best episode to watch. The pilot or “Through the Looking Glass,” the Season 3 finale in which Jack yelled “We have to go back!,” may have contained more “Holy shit!” moments or elicited more immediate reaction. But “The Constant” is an exemplary episode that displays the show’s great ambition, its equal commitment to genre and emotional narrative, a testament to the show’s overarching belief in goodness, and a display of storytelling that’s nearly vanished from television. It’s almost impossible that Lost would air on a broadcast network if it began in 2018, and it’s almost impossible to imagine the TV landscape would look the same without the show. “The Constant” is the purest reminder of what Lost could be at its soaring height, and that’s why the episode is no. 1 on The Ringer’s 100 Best TV Episodes of the Century list.

Every episode that earned a spot on the list is important. The Ringer powers that be selected episodes that were powerful on their own while also representing the ethos of their shows. Shows like Breaking Bad and Mad Men and The West Wing have multiple landmark episodes that could have made it, but we limited the list to one episode per show. (We also disqualified one-time specials, award shows, annual events like the Super Bowl, and made-for-TV movies.) That selection had to make a difference. In the case of Tom Cruise’s appearance on Oprah (no. 17), his celebrity—and in many ways, the nature of celebrity—changed forever. In the case of “Losing My Religion” from Grey’s Anatomy (no. 11), the American melodrama was revived and scored by Snow Patrol. In the case of the Beirut episode of Anthony Bourdain: No Reservations (no. 27), the implications of war were reframed for a mass audience. Each entry is worth revisiting because its craft or its vision achieves something different.

TV has become the medium of the collective—a medium that drives conversation and demands to be discussed. The episodes celebrated on this list all contributed to elevating TV, such that TV is no longer relegated to small-screen status behind movies. (Ask Julia Roberts about that.) An hour or less is enough time to make a lasting statement that impacts a broad audience. Sometimes that impact is reminding people that Justin Timberlake is prone to hysteria when his possessions get repossessed, just like anyone else (Punk’d, no. 30). And sometimes that impact is interpreting an ongoing national conversation about police brutality for a family-friendly audience (Black-ish, no. 74). In nearly 19 years, enough television has been produced to hit every note on the spectrum from ludicrous and absurd to vital and profound.

A common refrain in the streaming age is that there is too much TV. Between Netflix, Hulu, Amazon, the iTunes store, cable subscriptions, and network-specific apps, hundreds of television shows are available for consumption at all times. It can be overwhelming and difficult to navigate. The Ringer list of the top 100 episodes can act as a guide to help wade through the glut of options, because it’s worth the time investment. Television is great. The shows covered deserved to be discovered by new audiences or watched anew—because characters like Jed Bartlet and Snooki still inspire in their own ways; because Dexter and Tony Soprano remain as sociopathic and enthralling as ever; because Tina Fey and Jon Stewart are essential to understanding recent American history. Each of these 100 episodes made audiences feel something, and when considered in sum, it’s clear that the past 18 years of episodic television have been remarkable.