The door was open. I stepped down the gloomy passage and into the bright kitchen, and at once knew why I had come back.

Back to the Aran Islands, swimming under the paws of Ireland in the brash Atlantic. Back along the spine of Inishmore, staring at acres of limestone pavement left shining from an evening shower. Back to Kilmurvey House and the spacious kitchen of Bridget and Treasa Johnston Hernon.

The kitchen exhales a kind warmth, generated by the splendid old cookstove. The upright chairs littered around it are shiny with use, promising racy conversation and laughter. There are several aromas in the air -- the soda bread baking in the oven, the greasy black pudding fried at breakfast and the floury smell of boiled potatoes, the best I have ever tasted.

"It's Kevin, so it is!" says Treasa.

"Arra!" says Bridget, "it's Kevin at last."

Bridget is in her sixties now, and her daughter Treasa almost 30. They speak simultaneously, and both smile generous smiles. Together they preside over the island's most highly reputed guest house, twin hostesses at a kind of continuous house party attended by a succession of visitors, many of whom return here year after year.

I have come back to the Aran Islands after 18 years, and I settle into a chair as easily as if I had been sitting in it the day before yesterday. This kitchen will be my home base.

What will the weather be like tomorrow? Bridget will know. What should I pay for an Aran Islands' sweater? Treasa will tell me. More than that, the kitchen is a microcosm: The policeman arrives, or the priest, or the driver of a mini-van ... all to pause, drink tea, exchange local news.

Little happens on the islands that does not pass through the kitchen at Kilmurvey House.

When I first visited Aran, there was no electricity, only generators, gas cylinders and candles. Even now, high on the wall, a battery clock hums to itself. It is set wrong and hung crooked, as if to cock a snook at the importance of time.

"Days, months, years, Kevin!" says Bridget. "God, yes!" And then, brightening: "I'll tell you what. It's when you're working and you're happy, you don't notice time."

Ireland's eastern seaboard is relatively clear-cut. Land ends, sea begins. But the western seaboard is ragged and strewn with rocky outcrops, islets, populated islands. Inishbofin and Inishturk, Achill and Mweenish, Garinish and Gola -- a musical litany. People live on no fewer than 75 islands off the coast of Ireland.

The Aran Islanders -- the 1,350 people living on Inishmore ("the big island"), Inishmaan ("the middle island") and Inisheer ("the west island") -- are the most celebrated of Ireland's wind-swept communities. This is partly because they live in so desolate a place, on islands without trees, in little hamlets of low-slung cottages; partly because of Inishmore's stunning horizontal limestone expanse and its huge cliffs dropping sheer to the gnashing ocean; and because the scatter of ancient megalithic and early Christian monuments seem not to have been imposed upon the landscape but to grow out of it.

Inishmore is not for those who need spoon-feeding or who insist on having a shower in their rooms. It is for those who want simple clean lodgings, an unhurried pace and dramatic weather, who respond to time-honored stone acres, rugged shores and wind-tormented seas, and who welcome hearty food and unexpected companionship, the flickering of the fire and lively talk.

I sit in the kitchen of Kilmurvey House, listening to the young curate, Father O'Donohue, who has just come from the morning's six-monthly court proceedings in Kilronan. One man drunk and disorderly. Two men in a fistfight. Two women who went to the pub for lunch on the day of the annual First Communion and were still celebrating after the pub's closing hours, more than 12 hours later.

" 'When did the Communion begin?' asked the judge," reported Father O'Donohue.

" 'Eleven o'clock, your honor,' said one of the women."

"Arra!" cries Bridget, throwing up her hands, always so quick to seize the bright thread of humor in the fabric of island days. "The Aran Isles forevermore!"

Come to Inishmore by boat and you will land, as I did, at the little jetty in Kilronan, the island's only real village, though it amounts to no more than a spatter of gray houses with a couple of shops, several cafes and bars, two bicycle-hire sheds and a post office.

But no matter whether you're going to stay for a week or just for a day, the island's most dramatic and magnetic center remains the same today as it has for the last 2,000 years -- the spectacular prehistoric fort of Dun Aengus.

At first you don't realize quite how vast Dun Aengus is, because it was built with great hunks of limestone, much like the maze of stone hedges that give so much of the treeless island its unique hivelike appearance.

Erected by the Belgic Celts sometime between 500 B.C. and 100 B.C., Dun Aengus consists of three massive semicircular ramparts, the inner wall 13 feet and 18 feet high, perched right on the edge of a cliff dropping almost 300 feet to the Atlantic.

I sat as near to the edge of the cliff as I dared and listened to the ocean roar into the caverns underneath. Waves, unhindered by even so much as a rocky outcrop for 3,000 miles, smashed into limestone, rose in slow motion like dancers and collapsed again.

The sea spray was lifted on the fierce updraft, and I tasted the salt on my tongue.

We know that for centuries -- up to and just after the birth of Christ -- waves of Indo-European migrants moved west across the empty green face of Europe, overlapping, fighting, intermarrying, settling: the Slavs, the Germanic peoples, the Celts.

And here, on the edge of a stupendous cliff, with their backs to the Atlantic, the driven Celts made this one last stone stand.

Was Dun Aengus once circular? Did the cliff collapse and part of the fort drop into the seething water? Or was it, like one fort in County Clare on the Irish mainland, actually built in the shape of a horseshoe?

Was the chevaux de frise, an army of pointed stones raised and tilted against oncomers, erected around the ramparts to repel not only armies of wild men but also herds of wild pigs? Was the place used for trading, for sacred ceremony, for observation of sun and moon and stars, as well as for defense?

These are the questions archaeologists and historians have asked about Dun Aengus. And because there is so little agreement, there is still room for the nonspecialist to speculate.

I see Dun Aengus as a kind of symbol. I see it as standing for heroic last-ditch resistance, then and now, here and everywhere. I see it as the statement of a people with nowhere farther to go.

I have been searching for the riddle master, and I cannot find him. He is a man permanently employed by the Office of Public Works to maintain the ruins of the Iron Age forts and medieval churches on the island -- the Black Fort, the Church of the Four Comely Saints, Turmartin Tower and the Seven Churches, of which there are only two.

From time to time the man falls into conversation with passersby and asks them riddles. Sometimes he plays for a wager, say a pint of Guinness. Today, I learned, it was the turn of two Americans in Kilmurvey House.

"How can you tell Adam from the other people you will meet in paradise?" he had asked. They had cleverly guessed that Adam would be missing a rib, but the riddle master rejected that idea. He was, however, in no hurry to provide the answer himself.

Sitting in the warmth of Bridget's kitchen after supper, it occurred to me that the Aran Islands abound with unanswerable questions. It is a place of mysteries, stories of fairies trooping up at Black Fort and Dun Aengus, and of a recently deceased priest who still makes his rounds as a ghost, accompanied by a greyhound without legs.

All that seemed rather improbable as the everyday talk ebbed and flowed around me. "Agas, they're mighty cookers, but the price is fierce ..." "Tomorrow will be a bit whiskery ... " "Off you go now, and mind you behave yourselves."

This last directive was intended for me and my fellow guests -- a German woman returned here, like me, after a long absence, and a couple from Dublin. We were about to visit the local pub. Donning our hats and coats, we stepped out into the starless night. It was so dark that, in the name of a drink, we kept walking into stone walls. So we linked arms and, four abreast, advanced into the night.

Then out of the dark night welled a darker shape. The German woman gave a start and yelped. The shape -- a man if that is what he was -- walked right through us, and we through him, or it glided between our linked arms. We turned around, but there was no sign of him.

When I first came to the Aran Islands, I saw decline everywhere: few tourists, little fishing, the population dropping more than twice as fast as in the west of Ireland. The European Economic Community helped slow down this decline. New markets have opened, and Aran Islanders have found new income from increased fishing for lobster, whitefish (cod, whiting and flatfish) and prawn, and from smoking their own salmon.

Standing on a cliff top in the drizzle that slanted in off the sea, I talked to a young fisherman. Under his woolen cap he had dark curly hair and, like so many of the islanders, a long narrow face and clear blue eyes. With a single rod he had caught 70 mackerel in an hour and a half.

"And I caught 100 last night," he said, "so I did. And three times, I caught seven on the one line."

"Where will you sell them?" I asked.

The man was throwing the shining fish, all of them looking rather surprised, into an old sack lined with a plastic bag. "Oh, I'll sell these up and down the island," he said. "I'm only fishing to help pass the time." He said he fished from a curragh -- a canvas-and-frame boat -- for lobster, some of which goes to Paris and fetches a "good price" -- about $8 a pound, he estimated.

The Aran Islanders' association with the Continent is relatively recent, but like people throughout western Ireland, their links with North America are more than 150 years old.

Since 1820 more than 4 million people have emigrated from Ireland to America, and it is probably no exaggeration to say that every Aran Islander has a family association with America.

"There are 10 men off the islands in America working illicitly," one islander told me. "And I know of five more going out this month."

Some leave to work, then come back home. Eighteen years ago, I attended a ceilidh (music, song and dance) in a little cottage that lasted all night and only ended as mournful dawn was breaking -- in honor of an island girl who was leaving for Boston that morning. She has since returned, married and mothered five sons.

But most of the emigrants have stayed abroad. Builders and plumbers, carpenters and nannies. Their photographs adorn the front rooms of little cottages, keeping company, as often as not, with time-worn pictures of John F. Kennedy and the pope.

I went to see Mary Hernon, who, according to Bridget, is the best knitter on the island. She and her husband, Pat, both in their seventies, received me with the simple courtesy that is at once deeply refreshing and humbling to those of us who rush around and regard time as an enemy.

For a while we talked about the different stitches that go into the elaborately decorated Aran sweater. The trellis symbolizes the island's stone-walled fields; the basket stitch represents the fisherman's basket; the tree of life conveys family unity and strong sons; and the link is emblematic of the eternal tie between those who stay and those who leave home and travel to distant countries.

"Have any of your family gone to America?" I asked.

"Sure enough!" replied Mary. "I have five cousins there. My aunt is there too, and last week she asked me to knit sweaters for them. Six sweaters in all."

"That's plenty of work," I said.

"My aunt, she's my godmother," said Mary. "I wouldn't want to let her down. After my mother died, each year she remembered and sent me something."

For a while we sat in companionable silence. A donkey ambled up and looked in the window.

"More fishing," I said. "More tourists. When I was here before, things were dying away."

"Yes," said Pat, "things is changing."

"And we're dying away ourselves," said Mary. Both gently rocked and laughed.

For the moment, looking east and looking west, the Aran Islands enjoy a precarious prosperity. The fishing is good, though the lobster is in danger of being fished out. There is a little outpost of AT&T here, employing up to 30 people making cables. And from July to September, tourists arrive.

But for all this, there are simply not enough jobs to stabilize the population. Inevitably it is the young who leave, looking for work, unwilling to accept the inertia and claustrophobia of the long winters. While it is true that the Aran population is declining at about half the rate of the other Irish islands, the long-term outlook is probably no more secure than it was 20 years ago.

Mairtin Mullin, driver of one of Inishmore's ubiquitous mini-vans, has just invested his life's savings in a half-share of a new boat.

"Not new, Kevin," he says in that soft island voice.

"How old?"

"Twenty-five years," he says. "That doesn't matter. It's how it's made that matters. A boat can be five years old and finished, and another boat can live for years and years."

"Will you go out in it yourself?"

Mairtin shook his head.

"But it's profitable," I said.

Mairtin smiled a melancholy smile. "When winter comes with no visitors, and you have a wife and children, and there's more time to eat ..." His voice trails off. "Life's not easy on the islands."

The Aran Islands are changing, but they change slowly. They have not lost touch with their old values and identity. Gaelic, for instance, is still the islands' first language and is said to be spoken with greater authority and purity than anywhere else.

Some of the old folk tales and folk songs are still in currency; from time to time you can hear an old man break into song in one of the islands' pubs.

Curraghs are still used by the inshore fishermen. Made of tarred canvas stretched over wooden frames and drawing not more than six inches of water, the slender boats are rowed by two or three men with oars shaped like matchsticks. They bob and twist through the water and, when beached and overturned, look like basking seals.

The islanders' arduous way of life, fishing in the moody seas and wrestling a living from the intractable land, was celebrated in filmmaker Robert Flaherty's epic documentary of 1934, "Man of Aran."

"That film put Aran on the map for America," commented Bridget.

I had just come back from a screening of the film in Kilronan and was rhapsodizing about the way in which one astounding scene succeeded another: a boy casually sitting on the edge of a cliff, hooking fish almost 300 feet beneath; a woman lugging panniers of seaweed from the beach to the flagstone field where, with sand and grit and precious earth, it is used to build up beds for growing potatoes; savage storms and huge exploding waves; a man standing in the prow of a curragh, poised to hurl his harpoon ...

"Flaherty once stayed here," Bridget said. She got up and staggered back into the kitchen carrying a solid brass harpoon gun. "One and the same," she said.

In Bridget's kitchen there's a little sign on the wall bearing the legend: Whichever room I show my guests, it seems they like my kitchen best.

"What would you want your guests to go away with?" I asked Bridget.

"That's a good question," she said. Then, after a while: "I've seen people crying as they left here. It's not the place that makes a place. It's the people."

I never did find Padraig Dirrane, the riddle master. But then, it's appropriate for a riddle master to be elusive. If you should happen to meet him, you can give him an answer, the one I left with Bridget.

"Tell the riddle master," I said, "Adam won't have a navel."

"In the name of St. Anthony," cried Bridget, her eyes shining, "what are ye talking about?" WAYS & MEANS

GETTING THERE: There are daily flights on Aer Arann to all three Aran Islands from Galway in western Ireland for $80 round trip; there also is regular ferryboat service. The trip by sea takes about 2 1/2 hours in calm weather. During summer months, small ferries also operate between Rossaveal on the Connemara coast and Inishmore, an hour's trip.

WHEN TO GO: May to September is the most popular time to visit; warm Gulf Stream currents help make the winters relatively mild, though showery. Temperatures, as in western Ireland, average from 40 to 49 degrees in midwinter, and from 56 to 68 in midsummer.

WHERE TO STAY: Reservations for guest houses in the Arans may be made through Ireland's Central Reservation Office in Dublin (14 Upper O'Connell St., Dublin 1, Ireland, telephone 011-353- 1-735-209), at least four weeks prior to arrival in Ireland. In Ireland, guest house reservations may be made through any Irish Tourist Board office.

Bridget Johnston Hernon's Kilmurvey House (Inishmore, Aran Islands, County Galway, telephone 011-353-099-61218) is open May 1 through Sept. 30. Rates are about $20 per night, double, and include breakfast.

SUGGESTED READING: Pat Mullen's "Man of Aran" (E.P. Dutton, 1935) is a vivid, plain-spoken account of life on Inishmore and of his experiences with filmmaker Robert Flaherty. In "Aran Islands, a Personal Journey" (Doubleday, 1980), Dennis Smith recounts a visit to the Arans, with haunting black-and-white photographs by Bill Powers.

INFORMATION: Irish Tourist Board, 757 Third Ave., New York, N.Y. 10017, (212) 418-0800. -- Kevin Crossley-Holland