YOU KNOW ABOUT the couple who were married so long that they were on their second bottle of Tabsco.

Well, my wife said wer were out of nutmeg and Christmas was coming up..

We like thinkgs fresh off the vine so I checked the encyclopedia. The nutmeg, it said, was the hard, dark aromatic kernel of the nutmeg tree, indigenous to the Moluccas or Spice Islands in Indonesia, and now also grown in the West Indies.

So I went to the atlas and there it was: Grenada, Isle of Spice, southern-most of the Windward Islands, mean temperature 83 degrees. Now, where I come from, in the hills of western Massachusetts, an average temperature of 83 degrees is not mean in any way.

So I called a travel agent and booked us to Grenada, which takes just a bit of doing. First, we flew from New York by British West Indian Airlines (BWIA) to Barbados for an afternoon connection with Leeward Islands Air Transport (LIAT), the Caribbean airline that services the smaller islands. Grenada is only 21 miles long and 12 miles wide, and its present airfield just about handles a 48-passenger turbo-prop. We happened to get the 15-passenger Dove, but it winged us there in a jaunty (if somewhat sweaty) 45 minutes. However, as soon as I stepped out of the plane, I was sure I could smell spice.

The hotels are an hour's drive from Pearls Airport, and the narrow road ovver the rain forest mountain has 7,264 potholes, plus goats, chickens, cows and Grenadians walking both sides of the road. In addition, the nation is a member of the British Commonwealth, so you drive on the left-hand side.

With the above in mind, I would advise all and sundry to have a taxi waiting at the airport, which can be arranged when booking your hotel. The cost is about $30 in U.S. currency, but you leave the driving, the horn-blowing (double-beep is the custom when approaching every one of the almost successive blind curves) and the nerve-wracking to them.

The weather was warm and a touch humid when we arrived, but the trade winds wedded your body to the atmosphere in honeymoon bliss. Darkness comes quickly near the equator, and we drove along territorially disoriented but in complete harmony with the continual chirping of tiny tree frogs and the nicely counterpointed double-beeps that signaled another hairpin turn.

We were booked into the Spice Island Inn, which is on the Grand Anse Beach, two miles of the whitest sand framed by Grenada's lush green hills. Manager Desmond Campbell took us immediately in hand (it seemed to be the custom for the manager to personally get to know each guest), and a chilled drink of freshly squeezed passion fruit invigorated us.

At present, all the hotels on Grenada are small. The 184-room Holiday Inn burned out two years ago, and there is talk of its being rebuilt, but it seems to be one of those tomorrow and tomorrow and tomorrow deals.

Meanwhile, the small hotels come to a total of only 180 rooms, Spice Island being one of the larger ones with 20 beachfront suites and 10 pool suites with 16- by 20-foot private pools. An elderly English couple who arrived sans luggage sojourned comfortably in their pool suite for two days until their clean undies finally arrived.

This is where the uniqueness of Grenada is so important. By the second morning, we had lost all sense of time and, essentially, place. The lovely weather, the great beach with its white sand, the blue-green water just enough below body temperature to invigorate without skeletal shock, the marvelous food -- without doubt to us the best food in general in the whole Caribbean -- the friendliness of the Grenadians and the impeccable quality of the service that is rendered on all sides and on all occasions made it seem like the tropical paradise the brochures had promised.

As a bonus, the language is English. When the Grenadians talk fast, I'm not sure they can understand each other. One of the commonest expressions you hear is "What you say, mon?" But when they slow down, as they do for outlanders, it's good old, bloody English.

Then why, even in the so-called off-season when rates are 40 percent cheaper, were only 15 percent of the 180 rooms on the island occupied? What is the fly in the suntan ointment? Why aren't more Americans taking advantage of the reasonable rates, marvelous climate, beaches, food and service?

The answers are complexly simle. In 1979, 41 citizens who could no longer tolerate the repressive government of Prime Minister Eric Gairy set fire to the army barracks in the capital city of St. George's, routed the 300 soldiers, took over the radio station and established a revolutionary government which is still in power, with no popular elections in the imminent future.

The new government quickly became allied with Cuba and Nicaragua, which offered them material aid. According to Unison Whiteman, the minister of tourism (also foreign minister and minister of civil aviatione, the United States had ignored their requests for aid and refused to enter into any meaningful discussions or negotiations. When in Barbados earlier this year, President Reagan nailed it home with the statement that, "The virus of Grenada must not spread through the Caribbean."

So there you have it. The principal crops of Grenada are nutmeg, bananas, cocoa and tourists, and the market is depressed for all of them.

The irony is that the revolutionary government under Maurice Bishop, whose leaders range in age from the middle 20s to the middle 30s, is acutely aware that it isn't nutmeg, bananas or cocoa on which the future welfar and prosperity of their nation depends -- it is tourists. And not just any tourists. Europe is an eight-hour flight away, so the Grenadians know it is the American and Canadian tourists on whom their future depends.

Consequently, while the official government in Grenada rails at the United States and its policies in the world's legislative bodies, the Bureau of Tourism is spending nearly all of its advertising money in the U.S. and Canada.

There can be no doubt by any American who has visited there that the Grenadians like Americans. According to officilas, you can walk safely there at any time of day or night. In addition, 100,000 Grenadians live in the borough of Brooklyn alone, and the money that they send home is a major source of income for the island.

In addition, most islanders are devout, church-going Catholics, and, according to Unison Whiteman, 85 percent of the people own their little plots of land. Most of them are poor, but the climate and lushness of the soil, the sea teeming with fish, the availability of breadfruit, mangoes and bananas just for the picking, make it possible for just about everybody to live a relatively healthy life.

Something like 28 fruits and vegetables grow on the island, and most are in season all the time. One of the new government's more enlightened preachings is that the natural foods of the island should be utilized to the utmost.

A lady who was way ahead of the government on this is Audrey Hopkin, who with her husband, Curtis, runs the lovely Ross Point Inn. When the inn opened in 1952, Audrey Hopkin decided she was going to create cuisine from native ingredients. She studied American and British cookbooks and experimented with Grenadian fruits, vegetables and root crops whenever she thought they would work.

Our dinner at the Ross Point Inn was the gustatory highlight of our island stay. We started off with a lambie cocktail, which is conch that has been boiled and beaten into submission. The sauce was just spicy enough to bring out the sweetness of this marine snail, whose flavor is very similar to that of a bay scallop. This was followed by tannia soup, which blended the subtropical root tannia, first utilized by the Arawak Indians when they settled in the Windward Islands, with the Hopkin flavorings.

Then came a tender, delicious veal cutlet with mushrooms and saffron rice, deep-fried callaloo cakes (the callaloo plant is similar to spinach and is also utilized in a tasty soup, sometimes augmented with crab) and a christopheen casserole (the christopheen is similar to a squash, and the Grenadians use it as the base for very rich vegetable dishes). For dessert we tasted both the warm coconut custard made with fresh coconut and freshly grated nutmeg and the fareen pudding with wine sauce.

After a week, it was obvious you could drink the water anywhere on the island (it is carefully monitored) and eat any of the fruits and vegetables -- including those from the markets, which are great fun to visit, especially on Saturday mornings. You must make the acquaintance of the sugar apple and fresh mandarin oranges, a drink called seamoss and, of course, fresh coconut water. We had no digestive problems whatsoever, and we ate and drank everything with abandon.

One note of caution. The Grenadian white rum is something like 140 proof. One night at dinner, I ordered bananas flambe, and when they were flamed at table, it took 10 minutes for the alchol in the rum to burn out. Just a little dab will do you.

The Grenadians are presently building a new airport with a 9,000-foot runway just 10 minutes from the hotels and capital city. Once it's open, probably in eary 1984, middle-sized jets will be able to land from major North American cities both day and night, bypassing the present necessary stops in Barbadoes or Trinidad and avoiding the flightiness of LIAT. What affect this will have on Grenada is hard to say. They hope it will open a new era of tourism and prosperity with new, 150-room hotels near their 46 beaches.

But right now, there is no doubt that Grenada is one of the bargains of the Caribbean, both in season and out.