IT NEVER fails. If an artist has created a work with apparently universal and timeless appeal -- acclaimed by critics and public alike -- five will get you 10 that the artist himself looks back on it as a mere trifle, an unfortunate interruption in the serious flow of his career.

So it is with William Gibson, who does not otherwise make a habit of being predictable. The significance of "The Miracle Worker," the 1960 play that has stirred audiences of nearly all ages, nations and degrees of sophistication, is, to its author, chiefly financial. Along with "Two for the Seesaw" (another play that starred Anne Bancroft and was directed by Gibson's long-time friend Arthur Penn), it gave him enough of a cash flow to engage a business manager and then withdraw from the seamy world of live theater into the heavenly fields of literature.

Gibson spent most of the years 1960-67 writing "A Mass for the Dead," a memoir of his Irish-American kin and Bronx upbringing and, he says, "a much more significant piece of writing than either of those plays, which has been bought by about 12 people."

He had been writing for 20 years -- poetry, television scripts (including the original version of "The Miracle Worker") and a novel ("The Cobweb") -- before he became "hot." He has been writing for 20 years since then too, devoting most of his time to projects of more personal than commercial allure -- like "Goodly Creatures," his new play about religious strife in 17th-century Massachusetts, which opens Thursday at Silver Spring's Roundhouse Theatre.

Why the Roundhouse? Why Silver Spring? Physically, Gibson says, the Roundhouse is "one of the best theaters in America." But it is still a nonunion theater supported by Montgomery County tax dollars. It has never been known as a breeding ground for Broadway. To understand this eccentric decision, here's what you have to know:

1) If there is a rulebook for Broadway playwrights, William Gibson does not abide by it. He says he can get by on $5000 to $10,000 a year.On the road, at a very healthy-looking 65, he has living habits that would send the Dramatists' Guild into a frenzy. Passing up the playwritht's contractually guaranteed hotel room, he beds down in the nearest campground, as he did in Baltimore's Patapsco State Park during the run of his 1977 play "Golda" there.

"I hate hotels," he says, "and I love woodland sleeping. It was quiet, and I'd listen to the birds in the morning. I knew I was regarded as eccentric, but I thought everybody else was eccentric." (Everybody else included his wife, psychoanalyst Margaret Brenman, who stayed at the Lord Baltimore Hotel instead, when she came down for opening night from their home in Stockbridge, Mass.)

This time he has not been camping out -- "it's getting a little cold for that," he explains.

2) "I have a son who got very turned on to Eastern religious thought," says Gibson. Smiling, he adds, "Like many parents of my generation, I have such a son. And his interest in Vedic Hindu thought stirred my interest in Christianity. So I went back to church."

3) Going back to church, in Lenox, Mass., spurred him to write a passion play, a Christmas play and, finally, the first version of "Goodly Creatures," the story of Anne Hutchinson, a spiritual leader who almost took over the Massachusetts Bay Colony in the 1630s. Set in Boston, the play is "about a bunch of Christians who were endeavoring to live a good Christian life and ended up killing each other. They all share the same values, they all escape from the same evils. Everything seems marvelous and promising. They're in a virgin land. They're very lucky that a bad epidemic has wiped out half of the Indian population around them. They don't have to worry about any historical antecedents. And it comes out the same as with none of these advantages."

4) Gibson's friend John Edwards, a member of the drama faculty at the University of New Hampshire, had agreed to direct a play at the Roundhouse this winter, and last year asked Gibson if the play could be "Goodly Creatures." Edwards and the cast, headed by Paul Haggard and Beth MacDonald, have been in rehearsal since late December.

Gibson does not see "Goodly Creatures" going to Broadway, he says. "This production is an end in itself. It's not done tentatively. It's a very serious play, but I think it's fun, too. This gang has made it fun."

In recent years Gibson has written two plays that went to Broadway -- "A Cry of Players," with Frank Langella as the young William Shakespeare, and "Golda," with Bancroft, again directed by Penn, as the young, old and in-between Golda Meir -- but neither made much impact there.

"Golda," perhaps the one play Gibson has written with box-office factors prominent in his thinking, turned into a particularly grueling ordeal. In the fall of 1977, "Golda" looked like one of the best bets of that or any Broadway season -- until cantankerous audio-visual effects, unwieldy scenery, a backstage fire, the star's illness and dismal reviews combined to do the show in. To make the experience still more trying, it was closely (and critically) observed throughout by Golda Meir and large retinue of her family and friends.

"I've said everything I want to say about 'Golda,'" says Gibson. But he may have "Golda" in mind when he says, generally: "I can't stand any of my plays after they're written and produced. They're saturated with unhappy associations one way or another. I love to write. I don't like the production period so much. Generally the playwright is like a fifth wheel. He hangs around. A lot of what he wants to talk about with the director and actors he doesn't get time for." After a play has opened, "I walk away from it and I never want to see it again."

His own plays are not the only ones he finds forgettable. "There is something ephemeral about the theater," he says. In Shakespeare's day, when "the alternative form of entertainment was bear-baiting," the theater was a "compendious" force, says Gibson. "As people began to read, the theater lost that Olympian size that it had. It became a naturalistic theater, it became very tied to time and place, and it lost the sense that it was speaking to eternal verities. If you have a character say, 'I went to Macy's today,' in 50 years nobody will know what that means."

Not quite 50 years ago -- but nearly -- Gibson remembers seeing Alfred Lunt and Lynn Fontanne in Robert Sherwood's "Idiot's Delight." "Marvelous!" he says. "But you go back and see it today, and it all crumbles in your hands. There's an awful lot of theater work that disappears. That includes great names. You take a great name like Ibsen. If you have an enemy in the theater -- a producer -- talk him into doing an Ibsen festival.

"Now that's a very negative statement about the theater. That's the price most of us pay for working in the theater and what we get on the other side is you can speak with a directness to an audience that you don't get in any other art form. I have come out of the theater 10 times in my life, maybe, walking on air as I never have anywhere else."