Kuwait is an amazing example of how things even out - the rainfall is only 1 to 7 inches a year (about like a Washington spring weekend), there is hardly any soil in which to grow crops, and in any case the temperatures commonly reach 125 degrees Fahrenheit or, on occasion, 165 degrees.

And yet it is an immensely rich place, with some of the largest oil reserves in the world. Though oil was only discovered there in 1955, its annual production was a billion barrels a year by 1971.

As social problems go in a modern state there are few in Kuwait, it was said at the National Day reception Friday night, because oil revenues filter dwon through a welfare-state organization to the poor.

Ambassador Kahlid M. Jaffar received 1,000 guests with Mrs. Jaffar at the imposing house at 2940 Tilden St. NW, both of them in traditional Arab garb.

Arabs in general do not like the usual Western way of shaking hands firmly, preferring a very light pressure indeed. Americans, for their part, are quite slow to notice this, and go about crunching bones. As some of the guests can testify, however, one can learn this light pressure just as one learns not to yell.

Kuwait is almost entirely urban. Inland there is an escarpment, so that oil flows down into loading tankers by gravity instead of the usual pumps. Although the state is the size of New Jersey, it has only a million people, and many of these are foreigners doing business.

Ali A. Al-Sabah, press attache noted that guests from such companies as Gulf and Exxon were there; though one woman guest seemed put out that they were not the chairmen or presidents of those corporations.

"I never talk to flunkies," she said, having very high standards of corporation life.

Sen. Jacob Javits (R-N.Y.) and former Sen. J. William Fulbright (D-Ark.) may have qualified as non-flunkies, and so may Joseph Sisco, president of American University, though one is not sure of others in the crowd of academic couples from the capital's universities.

There are perhaps 200 Kuwaiti students in Washington, and most seemed to be present, looking much like students everywhere, with open shirts. Some of the men wore traditional Arab robes and headgear, and contrasted handsomely with the blue gauze and silver ceremonial dress of 6-year-old Sommar Al-Hameedi, daughter of the cultural attache, Mohammad H. Al-Hameedi and his wife.

It was important in the great crowd not to step on the children who blossomed here and there like flowers amid the aged timber.

The dining room was hardly to be believed for the crowd, even if one is familiar with Washington feeding troughs, and there appeared to be about an eighth of a mile of tables loaded with great roasts of veal and beef. No lamb.

"If there's lamb (as there often is at Arab feasts) a lot of people say they prefer beef; but tonight everybody wants lamb," said a carver, lost in the perversity of human appetites.

Huge rose-water ewers plated with gold held silver punch bowls full of crimson carnations above repeated clumps of candles, and great serving vessels held stuffed grape leaves, shrimp, crab and so on. It was a crowd ready to settle in for some serious eating.

In the great hall adjoining, the carved woodwork is from Damascus and the floors of Italian tiles are in Islamic designs, with a raised pool in the center, the rim forming a good place to sit.

Mary Marshall was among the many Western guests decked out fit to kill - deep purple-blue silk with silvery branches of plum blossoms enbroidered on it. With her was Sara Rock of Raleigh, N.C., in black wool and fur to set off her yellow hair. Men in the crowd looked pretty dull in dark business suits, though the French ambassador, Jacques Kosciusko-Morizet, wore a shirt brave with ruffles and flourishes. There were a lot of bankers - World Bank and so forth - and they are never festively got up, but the crowd in general was unusual for its effect of variety and color.

Despite its oil wealth - a per capita figure of $10,000 a year, making it one of the world's hightes - Kuait suffers the tensions of the Arab world in general. It was 70,000 Palestinian immigrant workers who fare far less well than native Kuwaitis, and who with immigrant workers from Egypt and India, do much of the drudge labor.

Kuwait was considered exceptional among Arab countries in its relatively advanced democracy, but the press was bridled some months ago when, the government said, it set one Arab nation against another and was regarded as an instrument of Iraqi propaganda.

Bordered north and west by Iraq and south by Saudi Arabia, Kuwait feels the forces of its larger neighbors.