They say Generation X, my generation, realizes it's grown up now. Two Gen X icons--Farrah Fawcett and Michael Jackson -- died within a day of each other this week.

It's hard to speak of a generation. Even the phrase "my generation" sounds so...Boomer--something that only sounds right when Roger Daltrey stammers it in a Who song.

But if the Boom can be said to have been the generation of sex, drugs and rock 'n roll, then Generation X was the generation of AIDS, crack and punk. If the Boom celebrated individuality while living the tail end of conformity, then Gen X can be said to be the product of that individuality, a group so diverse that its members resist any easy label, so separate that no one cultural moment defines it the way that Woodstock, Vietnam or the sexual revolution can define the Boom.

Gen Xers, known primarily for being "slackers," hit the cultural stage for their 15 minutes of fame circa 1989, then faded quietly into careers, parenthood and middle age. Much of the cultural upheaval of American life happened when Gen X was in elementary school.

Take Farrah Fawcett. As her obituaries make clear, Ms. Fawcett achieved celebrity (as opposed to fame) through her single season on "Charlie's Angels." Even then, it was not her acting or anything she did that made her famous. It was her trademark feathered hair (laboriously copied by every girl in junior high) and her habit of not wearing a bra that immortalized her. Everything else on her resume is only a footnote. And it was that certain poster, more than anything else, that made Ms. Fawcett so famous that for a few years in the late 1970s, she seemed to be all that the entertainment world spoke of.

That poster...It hung, for instance, on the back of my cousin's bedroom door. My aunt said he kissed it every night before he went to bed.

"She isn't wearing a bra," my mother observed, taking in the flimsy top of Ms. Fawcett's bathing suit, photographed on what must have been a chilly day.

"Doesn't need one," my aunt returned archly.

Typical comments of the Silent Generation on the Boom.

Farrah Fawcett is engraved forever on the collective consciousness as slim, tan and tousle-haired. Somehow that seemed like an immortal image, even as the woman herself aged. Now she is gone. It's hard to think of a lunchbox icon as being dead, at 62, of cancer.

Michael Jackson was different--a child star celebrated for his palpable talent, charisma and showmanship even at the age of 5. His performances fronting the Jackson 5 on "The Ed Sullivan Show" were spine-tingling. His rise was steady and meteoric. After achieving superstardom with his brothers, he struck out on his own. His solo album "Thriller" (1982) is still touted as being the best-selling album of all time.

Cable TV's then-new MTV music video channel offered Mr. Jackson novel ways to promote his music and showcase his dancing. The videos stand out even today for their creative use of the medium. And everyone, particularly, those in high school and college, saw those videos and danced to them. Mr. Jackson won eight Grammy awards for "Thriller".

Up to that point, Mr. Jackson had seemed the very embodiment of the moment in which he lived. In the early '70s, he personified the "Free to Be You and Me" ethos, with his huge Afro, bell bottoms and vests. In the later '70s he was the disco king, singing "Rock With You" to flashing silver disco lights. And in the 1980s he led New Wave cool with his fresh imagery and incredible dance moves.

But after that high point, Mr. Jackson's career took a long, slow dive into tabloid weirdness and disturbing allegations of child molestation. Whether the allegations were true or not--and a jury said not--Mr. Jackson's behavior was inappropriate by any standard.

His image as a sweet man-child ran up against disturbing realities on other fronts as well. He ruthlessly outbid former friend and former Beatle Paul McCartney for the Beatles back catalog of songs, and he included anti-Semitic slurs in his song "They Don't Care About Us."

His face, once cute, then handsome, morphed into a bizarre visage. He seemed to want to distance himself from everything that had once defined him -- his race, his gender, even his membership in the human species.

When he died, he was less an icon than a spectacle, a sad remnant of his former self. Whatever he had meant to Generation X had long since been swept away into the proverbial pop cultural dust bin.

It is only in the death of an icon that the icon's once unstoppable relevance is seen for what it really is: Stoppable. Endable. Mortal.

This may not be a new lesson for Gen Xers, the oldest of whom are now in their early 40s, but it is a sobering reminder. The icons of youth live on in images. And they are fleeting.