Monday, Feb. 1, 1982 — the first episode of NBC’s “Late Night With David Letterman” . . .

Larry “Bud” Melman (who was until this moment a 60-year-old file clerk and frustrated actor named Calvert DeForest) appeared on a darkened stage and delivered a perfectly amateurish welcome to a new late-night talk show in the after-Carson slot. Melman spoke in the manner of Edward Van Sloan’s cautionary prologue at the beginning of Boris Karloff’s 1931 horror film “Frankenstein.”

“Good evening. Certain NBC executives feel it would be a little unkind to present this show without a word of friendly warning,” Melman deadpanned. “We are about to unfold a show featuring David Letterman, a man of science who sought to create a show after his own image without reckoning upon God. It’s one of the strangest tales ever told. I think it will thrill you. It may shock you. It might even horrify you. So if any of you feel that you don’t care to subject your nerves to such a strain, now is your chance to . . . Well, we warned you.”

And then Letterman, gangly and bushy-haired and all of 34 years old, came out amid a small bevy of showgirls who wore enormous peacock headdresses that teetered precariously as they moved about. In his opening monologue, he made the first of a career’s worth of self-deprecating references to “Late Night’s” probable cancellation: “You folks are apparently a bright group — bright enough to read an applause sign, and I certainly appreciate that. I’m very excited about this new show and it’s a big three or four days for NBC. . . .”

So much of what Letterman’s show firmly and memorably became — so much of what it has meant to a culture that transacts first and foremost in irony — is seen right there in that first intentionally cheesy episode.

There were, and have remained, intentional air quotes around nearly everything about “Late Night,” which then became CBS’s stalwart “Late Show.” Later in the hour, Bill Murray came out as the first guest and, after a long and characteristically weird interview, performed a sloppy rendition of Olivia Newton-John’s inescapable hit song of the moment, “Physical.” It was a much needed exorcism ritual. I know sorority girls of the 21st century like to dress up in Day-Glo leg warmers and declare it “’80s Day” (so fun!), but if you remember anything about the actual 1980s, then surely you remember how oppressively vacuous most of the mainstream culture was, especially on television.

On May 20, David Letterman will host his last show, ending a 33-year career on late-night television. Here are some of his top moments from CBS's "The Late Show with David Letterman" and NBC's "Late Night." (Jayne W. Orenstein/The Washington Post)

Here at last, brought to us in the form of David Letterman, was a show that knew that there was a glory to be found in acknowledging the awfulness around us. “Late Night” was counterinstinctive art disguised as harmless filler.

Much more would come in that first decade, including the so-called “late-night wars” of the early 1990s, when, after 11 years on NBC, Letterman traveled with great buildup and fanfare (and a measure of spite) to CBS’s plum 11:30 slot, redubbing his hour “Late Show With David Letterman” on an extravagantly bright set in a revitalized Ed Sullivan Theater, for what adds up to the longest run in late-night TV. To this day, the air quotes of irony remain, but they are sometimes hard to detect because we’ve become so used to them in our everyday conversations. It’s an irony fueled by sarcasm. The baby boomers started it in the early “Saturday Night Live” era. It was a response to the relentless nonsense of advertising hyperbole and June Cleaver patterned-wallpaper happiness. Letterman mastered the use of mixing sincerity with an ever-so-slightly snide dismissal, insults he often lobbed at his own ego. (Let me demonstrate: Letterman’s career was “great,” he is “legendary,” I am “praising” him, with my “writing.”)

Letterman appears with host Johnny Carson on “The Tonight Show” in 1991. (Bob Galbraith/Associated Press)

CBS erected this billboard after NBC erected a billboard of Jay Leno, left, proclaiming his No. 1 late-night rating. (Lou Bopp/CBS via Associated Press)

Letterman, who turned 68 last month, hangs it up with his final “Late Show” on Wednesday night. His first guest, Murray, will also be his last, on Tuesday night’s penultimate show, which will include a performance from Bob Dylan. The plans for Wednesday night’s finale are under so many layers of wrap that even Letterman has claimed to not know what’s fully in store for his own send-off.

When writing about Letterman and considering his significant contribution to television — particularly funny television — it’s tempting to give in to completist urges and fall down the bottomless rabbit hole that has become YouTube, which offers clip after clip after clip after clip. More than you could ever watch, not only from a show that aired a day or two ago, but from the ancient years (let’s subjectively suggest the superior years?) on NBC. You begin to make up your own Top 10 list of his attributes — and his flaws.

The No. 1 best thing about Letterman and his late-night show — then and now, the thing we’ll probably end up missing most and root around YouTube years and decades hence in a quest to recall — is his Indiana-raised insouciance. We came to believe firmly, after so many magazine profiles that tried to crack the code of Letterman’s personality, that the secret to his success was to be found in his skepticism and casual indifference to hype. His challenge to celebrity status, folderol and ballyhoo is seen as a deeply Midwestern trait.

Even if it was mostly an act, that was okay, because we also understood the air quotes around his shtick; he also helped us understand the hyperbolic air quotes around our junk-culture lives: “politics,” “movie stars,” “fame,” “news,” “popular” and “comedy greatness.” For Letterman, the gee-whiz regard for spectacle is tempered by an instinctive worry that it’s wrong to show off. We responded to the dark and cynical sides of his personality that we might ascribe to the ancestral settlers and farmers of the American Midwest whose self-reliance led them to distrust even the weather. (Or to simply mock it. One of the most persistently repeated stories from Letterman’s early career is his brief stint as a TV weatherman in Indianapolis, predicting hail “the size of canned hams.”)

Letterman’s sense of irony was more than just a path to humor; it was one of the first and most dependable shields against a coming onslaught of celebrity rule. Are you like me? he would ask, all the time, setting up jokes from a place of folksy bewilderment at life. (“Are you like me, do you like science?” “Are you like me, do you like cheese?”) The answer we gave back to Letterman was yes. We were like him, or wanted to be. We knew that his mix of casual cheerfulness and skepticism would keep us safe.

Many of these earlier clips exist because they are duplicates of duplicates, tracing their origins back to the first group of “Late Night” fans were also among America’s first VCR nuts, obsessive-compulsive collectors who lined shelves and shelves with 120-minute videocassettes of “Late Night” episodes that were carefully labeled by date and guest appearances. While watching the oldest clips I could find, I was reminded of a guy in college who claimed to never have missed watching an episode, which was no small feat in an era before on-demand options and DVRs; he kept a journal in spiral notebooks of what happened on each episode. This didn’t seem crazy, somehow. It seemed like a worthy expression of devotion.

Madonna, left, and Sandra Bernhard on “Late Night” in 1988. (NBC via Associated Press)

Kid scientists take the stage on “Late Show” in 1998. (Alan Singer/CBS)

Watching these clips from old shows off and on for the past several weeks, I got caught in a nostalgic blur: Sandra Bernhard and Madonna flouncing around on stage in matching cutoff jean shorts and white T-shirts in an episode from July 1988, getting on Letterman’s very last nerve, seeming to make him incrementally nervous about what they might or might not do. A tearful reunion of Sonny & Cher from November 1987. Numerous appearances from Pee-wee Herman, Chris Elliott, the NBC Bookmobile lady and Melman with his “toast-on-a-stick” (and toast without a stick ).

Stupid Human Tricks, Stupid Pet Tricks. Shouting from the windows of 30 Rock to passersby below, just because. Throwing things off a high rooftop just to see what would happen when they hit the pavement in the alley below. “How about a beach ball filled with guacamole?” suggests a passing citizen, reading from a cue card. (And sure enough, SPLAT. It seemed like the funniest thing imaginable, because at the time it probably was the funniest thing imaginable.)

Lettermanese was by the mid-1980s a language most of us spoke fluently. Long before Internet access and well before the limitless choices of pop-culture niches, “Late Night” was one of the few shared signifiers or litmus tests of Gen X youth culture. The show would have on bands that we liked, that most of the world had not heard of yet. If you didn’t pick up an understanding and appreciation of “Late Night” in college, then of what possible use were you to us? Why have a boyfriend or girlfriend who didn’t like Letterman? Why share a bed with anyone who didn’t want to watch it in bed?

Julia Roberts makes her final appearance on “The Late Show” on May 13. (Jeffrey R. Staab/CBS)

Wednesday, May 13, 2015 — the 4,258th episode of CBS’s “Late Show With David Letterman” (and Letterman’s 6,077th, including the NBC years) . . .

An entire world has gone by. Oprah was displeased; Oprah was placated. The late-night wars ebbed and there was peace in the land for some time and then they raged again. There were actual wars, too — the kind with soldiers going away and many never coming home. The Internet, with all its cats, spoke Lettermanese with a far more ironic accent and took over our lives. The dam that held celebrity culture to a relative, tolerable trickle burst open and we all drowned. Letterman could no longer save us from the flood, but he did save himself (and the“Late Show’s” ship), by accepting it.

From “Late Night” to “Late Show,” things stayed the same in some essential ways. Paul Shaffer and the band are off to Letterman’s right, shattering all records of employee loyalty; the theme song they play each night is the same. The Top 10 lists, the dog tricks, the zany characters who come and go, the occasional street stunts. So much of it has not changed, but when you watch it now, after such a deep dive into the “Late Night” and “Late Show” archives, you realize that he’s the one who changed.

Steve Martin on “The Late Show” in 2003. (John Paul Filo/CBS)

Stephen Colbert will take over for Letterman as “Late Show” host in September. (Jeffery R. Staab/Associated Press)

Now he’s more of the Old Softy. Maybe it was the heart surgery. Maybe it was the near-miss with career immolation after the news of his office affair, the handling and outcome of which should be its own chapter in a textbook for damage-control experts. Maybe it was marriage and fatherhood. Maybe it was his obligation to keep spirits aloft in the aftermath of the Sept. 11, 2001 terrorist attacks.

Actresses stopped claiming to be afraid of Letterman. They learned long ago that the key was to flirt shamelessly with him and make him blush.

When there were only a week’s worth of episodes remaining, last Wednesday, Julia Roberts, Letterman’s favorite flirt, came by for a final appearance (she made 26 appearances in all since 1989). Like nearly every guest who has been on since Letterman announced his retirement last year, Roberts tried to heap praise upon him; Letterman made his usual show of humbly resisting, demurring, disavowing.

Roberts recalled her first time on the show, a billion years back: “I, as a fan of the show, did not want to come on, because I had seen you absolutely dismember young actresses of my kind of peer group. I thought, ‘I am going to go on and he’s going to know within 10 seconds what my IQ is and [be] like a samurai and Benihana me into pieces.”

“I’m not going to dispute this,” Letterman said. “But let me ask you this — what do you suppose was wrong with me, why would I behave that way? Why was it possible for you to have that perception, and I’m not arguing that the perception was false. I’m just saying, that if I was doing that, why?”

“I think because stupid people annoy you,” Roberts replied.

“Well, that answers the problem of my self-loathing,” Letterman said.

He has done all he can in the face of so much stupidity, often by pretending to the stupidest one of all. There came a point — and Letterman saw it, you have to believe that he saw it — where his style, his aw-shucks approach was no longer effective against so much noise and trash.

The night before this episode, May 12, Shaffer had mentioned to Letterman that he shared an elevator earlier that day with a young assistant to that night’s guest, Bill Clinton — one of the many people who were part of Clinton’s entourage. The woman turned to Shaffer and asked, “Do you work here?”

“We have to leave — now,” Letterman replied. The audience roared.

He’s right.

They have to get out while the getting’s good.

Have you seen how dumb things have gotten over on Jimmy Fallon’s “Tonight Show”? Are you like me, have you seen that attention-desperate nitwit James Corden’s “Late Late Show,” which began airing after Letterman’s show in March and is even more obsequious than Fallon’s? Do you find yourself recoiling at the late-night genre’s tendency to elevate the fawning, the self-absorbed? What’s going on with all the pretend cliquishness and all that fake sunshine being blown up mutual rear-ends?

Have you noticed how, on these shows, that it’s not at all about subverting the celebrity culture from within, but just rolling around in it like pigs in A-list mud? Have you noticed how it’s become a competition (literally) to see how well celebrities and a host can hang together and pay each other endless compliments? Have you picked up on the way that a lack of soul is covered by cleverness, giddiness, childishness?

If you’ve noticed all that, then I have terrible news for you: Your time might be up, too. Letterman’s most loyal viewers have to admit to ourselves that things have changed, that late-night TV, like most of TV, has changed (as it has every right to) and that humor itself has changed.

That glorious Frankenstein monster of a show that Melman alluded to in 1982? That monster put up quite a fight, but it has at long last met its end.

Late Show With David Letterman

final episode airs Wednesday at 11:35 p.m. on CBS.