Whom the gods would make mad, they first make rock stars.

It has been 15 years since Brian Wilson's breakdown transformed the king of California pop into Banquo's ghost. In the years since, the Beach Boys have launched at least three "comebacks," made periodic semi-successful forays onto the charts, and aired their internecine laudry all over the music press.

For the First Family of American rock 'n' roll, it's a blotch scrapbook.

The public image of fair-haired fraternity hangs over their career like a portrait in a corporation boardroom-yet lead singer Mike Love bitterly resents cousin Brian and contemptuosly dismisses cousin Dennis.

The Beach Boy leaped into progressive rock with "Pet Sounds" in 1966, a full year before the Beatles produced "Sgt. Pepper"-but in their 18-year recording career only three albums have passed the million mark, and all were "greates hits" packages.

In interviews they continue to deny that they feel imprisoned by their past, or even, that it dominates their work-yet their annual tours, including tonight's visit to the Capital Centre, include only a couple of newer songs; the body of the concert is 10 years old.

Their latest stab at a contemporary sound, the disco version of "Here Comes the Night," crested at a humble mid-40s on the chart. CBS has swung its support to "Good Timin'," a laid-back ballad that even Carl, who wrote it with Brian, admits is a throw-back to the 1963 "Surfer Gril" sound.

Sales of "new" Beach Boys albums have limped behind their peers' for a long time, but their live golden-oldies shows still pull vast and bouncing crowds.

Still they deny their fate. They will not lie back and enjoy their anachronism. Still Love babbles of their "'80s-style enlightment and upliftment." Still the group claims "Brian is back," when Brian's own bemused quotes contradict them.

The plain, painful fact is that we don't want the Beach Boys to grow up. We have other groups to reminde us of psychedelia and motorcycle leather and brittle, artsy New York and redneck reactionary Dixie and devolution in the heartland; but the golden Isle of the West, where no man has to work and women are effortlessly beautiful, will vanish with the passing of the Beach Boys into the real world. Brian Wilson created the American Avalon, and now he's interred in it.

"I don't think we represent America," Brian said a couple of years ago. "I think we represent California." It might be an epitaph. The Protester

If the tensions of an interview could be sketched out like a map, seemingly random remarks would resolve themselves into war zones.

"You know, there's a streak of insanity in that family," says Love, whose mother is sister to the Wilsons' father. "Their father was crazy, his father was crazy . . . but along with that streak there's a real creativity."

This speech is delivered with a reamrkable lack of inflection. It's a cold remark which embraces Dennis as well as Brian. Love doesn't like Dennis' irreverence, his risque jokes ("You wanna see an imitation of an elephant?" he asks the audience, pulling out the lining of his pants pockets), or the way Dennis can steal the show by singing "You Are So Beautiful" in a voice that out-cracks Joe Crocker's.

That neither the content nor the delivery of Love's temark sheds a particularly attractive light on him does not seem to have occured to him; he has his share of the Wilson Weirdness.

Love has never made such secret of irritation at Brian Wilson's reclusiveness and ballyhooed resurrections. Love is the Beach Boy who most bitterly resent the group's being stereotyped, who has tried to lead their image down the path of transcendental meditation to some latter-day hipness. Their involvement with Save the Children (a charity picked, it turns out, because they were invited to), as Love sees it, "generates a whole aura of good feeling, of harmonic and social consciousness."

According to legend (most strongly phrased in the recently published "The Beach Boys and the California Myth," by David Leaf), Love was the one who protested Brian's tampering with the waves-and-wheels formula back in the mid-'60s, the one who dreaded the loss of their fame and money.

Now, tending the embers of Brian's reputation as a genius before his time, Love acknowledges this conflict only obliquely. "Brian never thought in terms of commerciality. He wrote all these things in his head; we externalized what he cognized."

Love rolls out the lingo of the enlightened like an est barker; one half expects his name to have been adopted in some mystic ritual. He once had a reputation as a ladies' man; he's now contemplating hs fifth marriage.

His Jagger-ish choreography brings to mind Jagger's famous statement, "I don't wanna be singing 'Satisfaction' when I'm 40." At 3,, Love has no such qualms. "We're thw longest running road show in rock." The Cruiser

If any of the Beach Boys has an excuse for being "crazy" it's Dennis. He has always been the loner, the outsider. He was the last to join the group, the only teal surfer, the one who never got along with his father. Love recalls that the elder Wilson was "always beating up on him."

Dennis came close to mixing a little James Dean into the Beach Boy image. He was the cruiser, the sex symbol. It was primarily his reputation that got him picked up in Tucson for contributing to the delinquency of a 16-year old found in his dressing room. The morals charge was dropped, but the police handcuffed him twice, Dennis remembers, "for the television cameras."

He treats his body carelessly. In 1971, he smashed his hand through a glass door, suspending his drumming career for over two years. He syas he had an abdominal tumor removed several years ago, and that he has been seeeing doctors again for the past several months. His voice is ravaged from smoking.

He was an intimate of Charles Manson before Manson began to exhibit signs of insanity. They collaborated on a song recorded by the Beach Boys (although Manson was not credited). The Sharon Tate murders took a tremendous pychic toll on him.

All these tribulations have forged in Dennis a deliberate carpe diem consciousness. He is "crazy" in an engagingly nostalgic way. He believes in a good song and a good high. He shruggs off Love's disapproval (or anyone else's) living in the '60s and loving it there.

Not coincidentally, Dennis is the only Beach Boy to have struck out on his own with a solo album and a novie appearance ("Two Lane Blacktop"). He is currently collaborating with lover Chris McVie of Fleetwood Mac; he's working on a second solo album and a movie score.

He lives somewhat apart from the group. "I force myself to be normal, like I wash the car and go to the grocery. You can't just sit around like a vegetable."

His partial alienation from the group hurts but does not frighten him. "It's not just the Beach Boys in my life anymore." The Disciple

Carl is eerily like Brian these days, the resemblance heightened by beards and the childlike pudginess Carl has developed.He has Brian's aura of distance and maintains the same impassive expression. Outsiders exist only in his peripheral vision.

Carl assumed the musical leadership of the band when Brian stopped touring. Carl's even temperament is one reason; this resemblance is probably another. The group's old nick name, "Carl and the Passions," seems as wry as it was tongue-in-cheek.

Carl will go stolidly ahead where Brian would buckle. Argument rarely converts him. It tokk five years for his draft statuto be adjusted as he demanded: not just C.O., but wiht a proviso that he could work off his alternative service performing in hospitals, orphanages and prisons.

He has an implacable faith in Brian. Where Love will say that Brian's ability to focus on a session comes and goes," Carl will say clamly, "Brian wasn't interested."

He had the same absolute faith in the band. He ignores the commercial pressure for haevy sales: "We're achievers-we're used to that kind of pressure." He sounds not a little like a campaigning Jimmy Carter predicting the triumph of the "Light Album": "I intend for this album to be a success.

"I feel really blessed," he says. "The Beach Boys have been a really beautiful part of my life." But it is Carl, the disciple, who could give up the Beach Boys when it came time. "We've had our share. If it were right we'd quit." The Legend

There is an echo of Dorian Gray about Brian Wilson. While Brain ages and suffers hidden in his bedroom, the fictional Brian, enshrined in his music, remains unscarred.

The real Brian locked himself away for nearly four years in his Bel Air home, snorting cocaine and dreaming up melodies never heard again. The real Brian interred in a vault all the copies of an instrumental called "Fire" because he believed its "bad vibes" had caused a rash of fires in Los Angeles. The real Brian developed a severe weight problem and paranoid symptoms exacerbated by the use of LSD. The real Brian, during his infrequent appearances on stage, huddles like an infant behind his big white piano. (He is touring now, althoug his participation is minimal.)

The legendary Brian is still young and immensely creative and sensitive, still has the high, sweet voice that made his cousin Mike cry as a child (the voice now replaced by a producer Bruce Jhonston's falsetto). That Brian is a recording studio no pareil who lays down seemingly randon tracks until a masterpiece jigsaws together. That Brian is a perfectionist who made the group record "Wouldn't It Be Nice" over and over for two solid weeks before he was satisified. That Brian has the undiminished affection of the entire band.

That Brain in fact, is the Beach Boys' curse. "Brian is the Beach Boys," as Dennis puts it. "We're his messengers." They have been unable to navigate without him and unwilling to replace him. The strength of Brian's early writing has made the others' material seem pallid by comparison, fairly or not. There are times especially in concert, when it seems that the Beach Boys are a guard of honor for the once and future Brian.

At the side of the family portrait, in soft focus, stand Alan Jardine and Bruce Johnston. Jardine, a childhood friend of Brian, is a lifetime member of the band: calm, reserved, the only one whose marriage has survived since the early '60s. He and his wife, Lynda ("Lady Lynda") live in a canyon near Monterey, who share the barn with a recording studio. Jardine is not eager to be interviewed this go-round; "I'm sure the others have said pretty much the same things I would say."

Johnston joined the Beach Boys in 1965 and stayed until the end of '71. He's back now as producer and touring member on an indefinite basis. Perhaps because he is a little removed, Johnston has the brightest outlook on the band, and a kind of ingenous enthusiasm. He compares "Pet Sounds" to cult classic film, "Balck Orpheus." Of the need for a commercially successful album, he says, "We're musicians, not businessmen. It's not like we're Freddie Silverman and we have to have the top overnight ratings. It's like public television-quality and art."

At theCapital Centre tonight the arena will be nearly full, if not completely, and at least three of the band will wear ice-cream suits; and Bruce Jhonston will sing "I Write the Songs," since he did; and Carl will sing "Caroline, No" just like Brian used to and most of the women in the audience will want to mother Dennis and everybody will jump up and sing along when the band breaks into "Fun, Fun, Fun" and "Help Me, Rhonda" and "California Girls" and it will be summertime agian. Endless summertime. Implacable, immutable summertime. CAPTION: Pictures 1 through 4, Beach Boys, from left: Mike Love with Brian, Carl and Dennis Wilson