And it wasn't even the most idyllic vacation I ever had--three days were eaten up by a tumultuous nor'easter, there were no other children to play with, and we were ensconced outside town, at Monomoy.

Still, I roamed the storm-swept beaches in a slicker borrowed from my parents' friend, George Hutchinson, making me look like a forerunner of E.T. as I scavenged for shells and other treasures. I befriended a gull (or imagined I did), named him Chris and at dawn every morning watched from a split rail fence as he broke open his breakfast of mussels and scallops on the Monomoy Road.

I discovered a neighbor, Louise Schaff, who invited me to partake of a little library she kept for her grandchildren. There I unearthed and consumed, like a robin a fat worm, a book called "The Little Maid of Nantucket" that nourished my imaginings tenfold. And on good days, Mrs. Schaff loaned me a sailboat no bigger than a thimble in which I would bob on the calm harbor waters not 20 feet from shore. But in my mind's eye, I was sailing the stormy Pacific in search of the mighty sperm whale. Before that week was up, I had the Fever, but good.

My experience is hardly unique. The effect of the island on the visitor has been likened to that of the land of the lotus-eaters. Some people even believe the island is ringed by a force field of seduction protons, one that often is mistaken for a fog bank, through which no one passes unscathed. But others argue that it is really an epidemic of the Weathered-Cedar-Shingle Syndrome, a dangerous disorder robbing the retina of color perception within minutes of exposure. They say visitors to the island quickly lose their appreciation for anything that isn't gray.

"Gray houses, gray sky, gray sea, gray people!" they cry. "How quaint!"

Meteorologists put it down to something else altogether--a combination of salt, sun and unadulterated oxygen, and an atmosphere further unpolluted by billboards, neon, traffic lights or fast food. And local psychics explain it as The Curse of the Whaling Era.

Whatever the cause, Nantucket Fever spares virtually no one (and those it does, good riddance). And it is so contagious it can be spread by word of mouth, even word of pen. It also is highly democratic, though popular misconception has given it a reputation as a rich man's malady. Just as private yachts and private planes pour into Nantucket, so do the car and passenger ferries; just as there are rooms for $200 a night, there are rooms for $15 a night (Nantucket Accommodations, 617--228-9559, knows all).

Of course, people have been coming to Nantucket to restore their health and well-being for years. In the late 1800s, Siasconset, the village at the Eastern-most end of the island, was a health resort. They weren't so dumb. They knew the only "cure" for Nantucket Fever is more Nantucket, since it's a self-perpetuating affliction, and they made an honest business of it.

Nantucket Fever, then, is both chronic and galloping. The general course of the Fever is this: having laid dormant for the winter months, it pops up in the minds of the afflicted along with the crocuses. As it happens, this is fortuitous timing, because if you try to make ferry reservations any later, you better hope it's just your body and not your car you want to ship over (The Woods Hole, Martha's Vineyard and Nantucket Steamship Authority's automobile reservations are sold out well in advance).

It is well-timed in another way, too. Nantucket's "season," which formerly lasted from Memorial Day to Labor Day, in recent years has been stretched out to Columbus Day weekend--to allow all the Nantucket Fever victims an opportunity to procure the "cure" (the population swells from 6,000 to 35,000 in the summer on an island only 15-by-2 1/2 miles). But even those are false brackets, for the "season" really gets into swing in late April and lasts until mid-December. Dotted throughout this period are many splendid events on which Nantucket Fever victims often hang their period of rehabilitation:

* The Daffodil Festival (April 22-26): Ten years ago the Nantucket Garden Club, assisted by members of Nantucket's artist colony who donated their work to benefit the effort, undertook the task of bedecking the island with daffodils. To date, more than a million bulbs have been planted and to celebrate their annual blooming, a bevy of activities has evolved. The centerpiece of the fete is an antique car parade (April 23), featuring vehicles from the 'teens up to the '50s. The parade follows the 'Sconset Road, the yellow and white trumpets of thousands of daffodils lining both sides of it. A tailgate lunch, often resplendent with the excesses of the individual drivers (candelabra, crystal, and other wondrous absurdities), concludes the parade in 'Sconset.

In addition to the parade, the Garden Club sponsors a two-day Daffodil Show, featuring different varieties and arrangements of these flowers, on Monday and Tuesday (April 25 & 26) at the Harbor House. And all the store windows on Main Street are decorated with daffodil displays. Springtime never had a finer tribute.

* Sealegs Classic (May 29): The gun that starts this five-mile road race also heralds the beginning of the official "season." Sponsored by the Nantucket Easy Striders, the eight-year-old race follows a dirt course from the Miacomet Race Track to Bartlett's Farm, along the South Shore, then back to Miacomet Pond and the track. The race begins at noon, anyone can enter--some 150 runners, mostly vacationers, entered last year--and the cost is minimal. If you don't want to run, it's fun to watch.

* Opera House Cup Race (Aug. 21): Sponsored by the Opera House Restaurant, this is a race to the mainland and back for woodenhulled sailboats. So spectacular and beautiful is this race, it draws wooden boats from all over the East Coast, 70 in all last year. It is a handicap race, based on an old Cruising Club of America formula, open to single-hulled boats 32 feet or larger. The winner's name is engraved on a perpetual silver cup displayed in the restaurant's bar and the boat's name is placed on a quarterboard and hung permanently in the restaurant. Best viewing is, of course, from the water; but if that's impossible the next best viewing is with binoculars from Cliff Road, or, from Brant Point Light or the Jetties.

* Columbus Day Road Race (Oct. 9): Just as the official season begins, so does it end--running. This 10-mile road race begins in 'Sconset at the Water Company, goes through the town and out along the Polpis Road toward Nantucket town, ending on Sparks Lane at the Boys Club. Last year, the race drew about 130 entrants and has begun to attract Boston marathon and international runners. The race begins at noon, is open to anyone and the entrance fee is, again, tiny. Small prizes are awarded and a party for the runners follows the race.

* Christmas Shoppers' Stroll (Dec. 10): This island-wide block party features a rare appearance of the Venerable Christmas Spirit of Old, an endangered species throughout America. Sponsored by the Chamber of Commerce, the Shoppers' Stroll sees every store on Main Street thrown open for a party, each offering its own special form of Christmas cheer--from clam chowder to Irish coffee--all on the house and with no obligation to buy.

The evening begins with t e switching on of the Christmas lights on trees lining both sides of Main Street. It then proceeds to caroling, a pageant, a parade and, best of all, Santa Claus (virtually his only appearance on Nantucket, no street-corner impersonators here). Rain or cold, and always in the dark of night, Santa arrives in a horse-drawn carriage. He then holds forth at the foot of Main Street, where the children gather around him, their eyes full of awe and incredulity. And one by one they climb on to his knee for that very special consultation. This is truly a night to remember.

It took me 13 years to get back to Nantucket after that week in 1959. The urge never abated, it only grew. A grown-up by then, I was bent on reclaiming the rather sizable chunk of my heart I'd left behind all those years before. I found it, of course. And not surprisingly, I found it had taken root. Typical of Nantucket Fever, it is the island that claims you, not the other way around.By Kate Stout; Kate Stout is a New York writer--who would rather be in Nantucket.