Years ago, when people grew up knowing exactly what stilted language to use in answering this invitation or that and formulas of introduction were as carefully calibrated as those rules of the road that say that if all four cars show up at an intersection at the same time, it is car X that gets to cross first, Memorial Day was not just a day to mourn those who had died in war, it was the day on which one could unpack one's whites.

Wearing white was a sign of summer, and only the crudest person would appear in white shoes before that landmark day at the end of May.

Since we are now safe within the season, let us plot the whites of summer.

Wine, of course, and why not have a wine tasting to let your friends help choose the white wine that will see you through the season? Visit three or four liquor stores and ask the person who buys the wine to recommend several moderately priced whites. Every year there are bottles that are extremely good buys -- under-priced because of the value of the dollar, or because they are loss leaders or just because.

The usual measure is to figure six glasses of wine to a bottle and that, plus a knowledge of your friends' capacity, will help you to decide how much wine to buy; after all, you don't want to wind up wijth 12 half-empjty bottles. Before the guests are let loose to drink their fill, they must sample each wine and rate it. And, when you've discovered the wine favored by most of your friends, you will have your house wine for the summer.

Goat cheeses that are white as white can be are now available in gourmet stores in bewildering numbers and an awesome range of tastes; goat's milk, like cow's milk, will pick up the flavor of what the animal has eaten and when the cheese is good, it is very, very good and when it is bad it is horrid. Serve the cheese with white, unsalted crackers and white grapes.

Gin, vodka, rum and tequila are summer whites as well. For one dinner party, make a pitcher of martinis and offer guests that as a pre-dinner drink: straight up with an olive and with a Noel Coward record playing in jlthe background to set the period. For another, prepare a batch of margaritas and, oh, why not, put on a recording of a flamenco guitar or a mariachi band.

For your next white night produce a shaker of daiquiris. You will still have vodka to look forward to (stir three parts vodka together with one part Rose's lime juice and add a slice of lime for a vodka gimlet) and if you entertain often, cruise the liquor store with an eye out for white: framboise and champagne, or create your own drink using kirsch or poire or slivovitz or any of the crystal clear eaux-de-vie. You will be amazed at how many of your guests, offered a special cocktail, will make that adventurous leap away from white wine.

Oh dear. If only you had had the forethought last winter, you could have frozen a whole batch of snowballs and invited friends to a snowball party. Vanilla ice cream scooped unto rounds and sprinkled with chocolate and when your guests thought that was all, you, you clever thing, could have pelted them with real snow. Turn the calendar to December and make a note to stock up on snowballs. A good host thinks ahead.

Forethought is not necessary for a croquet tournament, only a patch of flat lawn and a croquet set. The American version of the game comes with mallets with small heads that are used to knock equally small balls through the wicket. The English version, favored in official tournaments and much more expensive to buy in this country, has larger mallets and larger balls, easier to hit until you discover that the wickets are smaller. Unless you are planning a carrer in croquet, buy the American version and spend your money on food and drink. When you issue the invitations, inform your guests that all participants must dress entirely in white.

Think how pretty it will look, the women in billowy dresses and straw hats, the men in white flannels and white shirts against the green grass. Think how deceptively innocent it will all appear as each participant faces the first wicket and plans how best to ruin the rest of the players. If you do not have enough white wicker chairs to seat the observers, spread white cloths on the grass. Remember how hard it is to get a grass stain out of white?

To the side of the croquet lawn, far enough away to be safe from balls that have been sent into oblivion, set up a table (covered with a white cloth centered with a bowl of white flowers) where there are tea sandwiches set out on a silver tray and a large silver bowl filled with champagne and slices of ripe, white peaches.

And if someone says, my goodness, what a lot of bother, you will say no, keeping to your theme by telling a little white lie.