WE ALL hate to see the old crafts untaught, the old skills forgot. Hardly anybody can thatch a roof any more, and I doubt there are a thousand people in Washington who still know how to cut through two bodies with one stroke of the sword.

Nostalgia having set in on the town, I visited Capt. Roger Pineau down at the Washington Navy Yard, where his Navy Memorial Museum is a sort of retreat from the plastic fripperies of today, and where the heady spell of yesterday is still cast.

He has rounded up some splendid samurai swords to display for Christmas. Well, we sat around after hours and he brought out these dates stuffed with walnuts (private stock).

"The sword of every samurai," he said, "should be fine enough to cut off a man's head with one clean swipe."

"No, no dates," I said, "because I think I see some calories loose in that one."

"We'll split one and each have half," he said, drawing a knife and slicing (YAH!) right through the walnuts and all. If I had not been so hungry I would have died before eating anything so gruesome. In between fainting spells, however, I admired an inscription of gold, cut and inlaid in the steel tang of one samurai blade.

"It certifies the blade was tested by cutting through two bodies at one stroke," said the captain. "A fine one."

Like most other persons who carefully avoid stepping on beetles or carelessly squashing wooly bears, I have a considerable aptitude for gore, nevertheless, and asked how you, ah, got the bodies to test the sword on.

Like everything else the Japanese have done, the testing of swords was an art.

You must not suppose that all Japanese warriors were refined men, however. Some of them merely saw a peasant and whacked him in two in a meadow, to test their sword. It is true they had a ceremonial brief statement telling the peasant they were testing their sword on him, but prudently got on with it without dawdling for a response. (The Japanese peasantry often did not learn the correct responses, any more than they mastered the tea ceremony or gained any competence in judging carp, irises or any other elegance of the empire.)

One drunken bum passed out on the side of a road, the ancient Japanese tale goes, and during the night three samurai on horseback took swipes at him to test their swords, but they were not good swords - or perhaps not good swordsmen - and merely bruised him severly. When the drunk recovered the next day, he complained that uncouth fellows had roughed him up. Never knew of his narrow escape.

But apart from informal testing, there were ceremonial testings on live men. Officials, properly costumed for the occasion, made official records for the archives. There is no history if things are not recorded.

Capt. Pineau can explain the various styles of testing swords on living bodies. Each style has, of course, its own Japanese name. In one good method, the men are seated cross-legged on a low platform and cut through the pelvic girdle. One famous blade cut three men in half at one stroke, using this method.

The persons on whom the tests were performed were said to be condemned criminals.

If there was a shortage of these, corpses could be used, once the heads were cut off, but they had to be set on inclined planes of sand, or you could damage the blade.

Capt. Pineau thinks some of the details may be a trifle grim. But if you go around asking questions about inscriptions you get an answer from him.

When the captain is not testing his blade on the convicted stuffed dates, he runs the museum, which formerly had a pink submarine out front, until [WORD ILLEGIBLE] decided black was a less giddy color for a military vessel.

Pineau, once managing editor of Smithsonian publications, is himself rather a historian, and was assistant to the late Adm. Samuel Eliot Morrison, the celebrated naval historian. Pineau is also rather a student of the Japanese language, and frequently corrects barbarisms in books where the wrong characters is printed by authors unfamiliar with written Japanese.

The golden period of sword-making was around 1300 A.D., but like Egyptian sculpture or hooked rugs in the Southern mountains, there are numerous styles, periods and masters.

To the samurai, the sword was symbol of all that makes life important, and early developed religious significance. The core of the sword, its fused sheathing of steel, the details of the forging and folding, the various angles and curvatures of the blade, and of course the remarkable ornamental furnishings (almost never on the blade itself) can be a lifelong study, and indeed are treasures of miniature sculpture.

The ones being exhibited for the next few weeks at the musuem are full of beasts and flowers. Cherry blossoms are very good for a sword - so are the single camellia blossoms, I have been told - since those flowers shatter after a brief glory. The blooms drop all at once, especially the camellia.

This reminded the samurai of his probable fate by decapitation from another samurai. I read somewhere, Capt. Pineau thinks cherry blossoms serve the same purpose.

The collection, shown earlier at the Military Academy at West Point, is privately owned by a young fellow only 31 years old, and the swords are predictably valuable, like most other antique examples of exceptional skill and art.

"Another date?" Pineau inquired.

In Japan, where standards have fallen as sharply as here, the kamikaze pilots of the war were given swords with which to disembowel themselves shortly before crashing their planes into enemy ships. Those swords were machine-made.

Not the magnificent workmanship of the old days.

They lost the war of course.

In America, we do not execute people and test swords at the same time. We use the American humane methods, Gary Gilmore, etc.

The national traditions of our sister nations sometimes seem to me curious, but different strokes for different folks, as they say. In Japan nowadays they test swords on bundles of damp rice straw, and while I never like to criticize foreigners, I doubt the swords are as properly tested as the ones in the Navy Memorial Museum.

But everywheree it is the same. Makeshift, Slapdash. Any which way. Craftsmen hardly care any more.

This same day, I visited the National Archives, which is proud of a new cartoon film explaining why we need archives. As I got it, we need documents to back up assertions. How do you really know Lincoln was born wherever he was born if you don't have Class A documentary evidence?

They have a lot of film, at the Archives, and I saw Bob Hope entertaining troops, Hitler at home in Bavaria, the Lindbergh baby in his perambulator and other wonders. I know we need to keep stuff - and rarely throw anything at all away, myself - but there are days I think a good fire would sort things out.

Brooding on the 3 billion documents at the archives and the collapse of standards in Japan, I dropped in for hamburger and coffer at Lynard Bros. Restaurant at 4th and C Streets SW. For years this has been the McSorley's of the neighborhood.

But even here the world has gone to hell. Alexander Lynard: who runs the place with his brother George) says they are tearing down the building to put up one of those motel-chain inns.

"My Daddy came here from Greece, and started his restaurant in 1920 down at 7th and Pennsylvania. They tore that building down for redevelopment, so he moved in 1932 to 11th and Penn., then then they tore that building down for redevelopment, so in 1959 we opened up here. Now they're tearing this down for redevelopment, and on Dec. 23 I'm calling it quits."

"You're too young to retire," a customers said.

"Year," he said.

(Noel, Noel.)