"No fruit tree," wrote an anonymous author in Gourmet magazine in November, 1969, "has exerted so profound an influence on the growth of civilization as the olive. It has provided the sustenance, the means for survival, in all the countries of the desert fringe in which it grows. The rich, oily fruits have shaped the whole character of the Mediterranean, the distinctive flavor of its food."

The olive early became for the Mediterranean world, Horizon Cookbook noted in 1968, "the basis of all cooking." No other fruit, it added, was as versatile.

These modern opinions followed venerable examples. Plato, a light eater because he had a delicate stomach, decided that olives were his favorite food.

"Except the vine," said Pliny, "there is no plant which bears a fruit of as great importance as the olive." On another occasion he observed, "There are two liquids especially agreeable to the human body, wine inside and oil outside." The ancients anointed their bodies with scented olive oil in Pliny's time, but for a much more practical reason in Homer's - to keep warm in winter.

These tributes to the importance of the olive may seem exaggerated to us since we are conscious of it either as an appetizer or garnish, as a source of oil for salads and cooking or as a tidbit in the depths of a martini. In short, a fruit whose disappearance we would hardly notice.

But in ancient times the olive was often the principal dish. Its oil is not merely a member of the family of vegetable fats. It is unique among them having a decided character irreplaceable by others. It is in this role that the olive over a period of 4,000 years or more has shaped the cuisines of the Middle East, Greece, Italy, Spain and southern France.

In the Mediterranean area, the native land of the olive, diet was at first frugal and limited. The importance of the olive was enhanced by a lack of competition. The everyday fare of the everyday citizen was bread (or gruel) of wheat, barley or millet made palatable by cheese (goat in Greece, sheep in Rome) or by vegetables, of which the commonest were garlic, onions and olives. Of this trio, the oil-rich olive was the most nutritive.

The ancient's day began with a meal which has been described as bread with a relish. The relish was often a few olives, or simply olive oil used as a moistener. Catalan peasant children echo the ancient breakfast today when they are given el pa y al , a slice of bread rubbed with garlic and moistened with a few drops of olive oil.

In more elaborate dishes, olives entered as the principal, or one of the principal elements, not simply as a condiment. Horace wrote that he preferred olives to guinea fowl or pheasant. This may seem a curious comparison, unless you are familiar with Middle-Eastern food where the olive is still used as an important ingredient.

Olive oil is different from all other common vegetable oils (there are minor exceptions, such as walnut oil) in that the others are neutral. You might say their function is mechanical rather than gastronomic. They moisten salads or provide a cooking fat to keep food from sticking to the pan. It is not their function, however, to alter the taste of a dish by adding flavors of their own. Olive oil, on the contrary, contributes both flavor and nutrition to any dish anointed by it or cooked in it and thus becomes a full-fledged ingredient.

In ancient times not only was olive oil a sort of liquid undergarment to trap body heat or a perfume (we have found other cosmetic uses for it today, to counteract dry skin or dry hair), but it was also a cleanser. The ancients had no soap and used olive oil instead. It was a medicine too, which Homeric Greeks, biblican Hebrews and ancient Romans believed capable of penetrating the skin and communicating health and longevity. Today we know that the olive tree contains salicylic acid, the active principle in aspirin. Burned in earthenware lamps, olive oil provided the most convenient source of light.

The olive is a hardwood tree whose close-grained whorled wood is beautiful and strong. According to the Bible, olive wood was used for the tabernacle in Solomon's temple. In Hawaii, it was used in earlier times to make spear shafts and in more recent ones, for adz handles, both of which require sturdy wood. Many foods - tuna, sardines, anchovy fillets - are preserved today in olive oil.

In Spain, meat is sometimes kept from spoiling by immersing it in olive oil. And ancient Egyptians supposedly used it to move obelisks and stone for the pyramids. Even in ancient times, the pulp which remained after the oil had been pressed from olives was not thrown away, but used as fertilizer or fed to animals.

It is not surprising that ancient Jewish law forbade cutting down a tree so valuable even if it belonged to an enemy. The Spartans, however, systematically destroyed the olives of Attica in an early version of economic warfare.

In an ancient world at the subsistence farming level, a single large tree would give an average family all the fruit it could eat and all the oil it needed for cooking, lighting and anointing. In our time, olives were so vital for existence in parts of the island of Corfu that the price paid for a parcel of land did not depend on its acreage but on the number of olive trees growing on it.

Olive oil was one of the most important commodities in international commerce for many centuries in ancient times. Crete may have been exporting it as early as 2500 B.C.; olive oil was probably one of Crete's main sources of revenue.

Athens made the political decision to abandon raising wheat in Attica in favor of olives and obtain wheat by selling oil and wine. It was the other way around in Pompeii where wine was more important than oil. But Pompeii nevertheless exported not only oil but also whole and pitted olives. As late as the middle of the second century A.D., the only Roman cities outside the capital which were prosperous were those of the Campania, such as Naples, Puteoh and Capua, whose economies depended on selling olives to the rest of Italy.

The olive was important not only to ancient economy but to ancient ecology as well.

"At the beginning of the sixth century B.C.," Reay Tannahill wrote in "Food in History," "Solon forbade the export the export of any agricultural produce other than olive oil . . . Such fibrous-rooted trees as remained were felled for the sake of the olive, whose deep-striking tap root soaked up the moisture far down in the limestone and did nothing to knit, conserve or feed the topsoil. By the fourth century B.C., Plato was gloomily contrasting the bare white limestone of the Attica countryside he knew with the green meadows, woods and springs of the past. The pure and brilliant light which is so startlingly characteristic of Greece today had been bought at the expense of the trees which had once kept the land fertile."