THE MAIN task of the Washington resident is to avoid Union Station if at all possible since it hangs like a pall over the cheerful spirit, reminding one and all of the ease with which madmen accomplish their desires, such as digging great holes in an otherwise beautiful and useful structure and calling it a "visitor center."

Now, of course, there is some chatter of converting the mess back into a railroad station, and this may cost even less than rebuilding Atlanta after the fire. They think they will keep the big hole, however, which is designated somewhere as a "theater" and which makes a nice detour on your way to catch a train once you learn you do not get the train in the station but in a shack somewhat this side of Baltimore. The hole would be a good place to put things.

My experience is that since nobody knows where any city bus goes, except the one he rides home, you should not catch buses downtown because they have a way of winding up at Union Station, where there is not merely the National Visitor Center to make you sad, but also the torn-up streets and mysterious traffic patterns that have been fluxing since the Cretaceous and will not actually be completed or clarified in our time.

STILL ALONG with avoiding the station, I had other important projects and needed to get a form at the building-permit office. Knowing not to get near a bus, I set out afoot and was able to be a Good Samaritan along the way. A fine, large woman was running towards a bus that had closed the door, but I hollered "Hold the bus" to the driver who, for a wonder, did so.

"I wanted the other bus," said the woman. And they wonder why men are not helpful nowadays.

At the permit office, which closes at 3 p.m. as everyone knows by instinct, a surprise awaited.

"I don't think you even need a permit for a shed that little," said a man. It's 30 square feet, and the city would be the better if more building were that size.

"I don't think so, either," I said, "but maybe there is somebody who can say flatly what the law is."

Sure enough there was. I have learned to spill the beans with bureaucrats, so they don't say later, "Oh, but you don't tell me it was going to have wood in it" or something. It is also well to phrase the main question ("Do I need the permit?") three or four different ways, just to make sure. No scret was withheld. It is going to sit on the ground, etc.

To my delight, the great authority understood it all perfectly and had a clear idea what a small shed is. It is a warning and rare experience to find an office that allays anxiety instead of raiting it.

This session with bureaucracy was so heartening that I almost stopped by the National Gallery to take that double-decker bus over to the National Portrait Gallery.

But there is no point feeling invincible, so I let the day pass with one happy experience. The last time I tried to ride the doube-decker, I knew enough not to trust the sign that said it would leave at such and such a time, so I asked the door guard.

Yes, he said, it leaves when the sign says, and you just stand there by the bus that was right in front of us. When it didn't go, I discovered a driver (one learns these arts) who said no, it wasn't running today.

"Maybe it would be a good idea to stick up a notice on the bus saying it isn't running today, so we don't just stand around waiting for it," I said.

"We don't have a sign like that," he said.

Besides, he went on, if I had checked inside the Gallergy - with Titian, perhaps - instead of the guard, I would have known the bus wasn't running.

But it is easier said than done.

Picking up a book at the Martin Luther King Jr. Memorial Library a bit later, I was pleased with the efficiency with which my present card (expiring in 1978) was declared invalid because there is a new kind of card, but I got the new in less then five minutes; and the new improved system takes only slightly longer to check out books than the old system.

A guard and some tunnel-type barriers (to make sure I was not stealing books) delayed my exit only slightly.

The primary aim of all computer systems, in libraries as elsewhere, is to hold down unemployment among computer specialists who would otherwise be on the dole. So I do not in any way object because the computers themselves are not monsters but our faithful servants, and of course a large crew is required to feed and water them.

I know of a Bethesda girl who has gone to Tennessee to raise mules, and not, why not. I love to think of distant I wonder if she is computerized and if places and how we are all bound together in one great chorus of life, Mules and everything.

As you know, for example, the war in Ethiopia has interfered greatly with the production of thistle seed this year - the Audubon Naturalist Society cannot get any for its forthcoming bird-seed sale, thanks to Ethiopia - so no man is an island.

By midnight, my labors over, I got home to hear the last half-hour of a Mozart opera on television.

I prefer to listen, rather than see. If you listen, you can hear what Happy Hour in Heaven sounds like; but if you watch the action on the screen, you see it is merely a gang of humans wandering around in some bushes trying to figure each other out.

A seduction scene in Mozart, threatening a girl, sounds like a sung prayer for blessings to descend on a new bishop, and those who are have only heard the music are invariably startled to see what it is actually going on.

So much the greater genius of the man. We would say, oh, it's just a bunch of nuts wandering about in the high grass all mixed up; but to Mozart there are no chiggers (a thing that worries one, viewing the last act) in that grass, and all the baffled folk sound off like angels.

Angels day. The building permit, the library, the false hope of helping the plump lady catch the bus; the complaining mail - he may sue, he says - the weary feet.

And at last the music. Only half an hour's worth. On such a night stood Dido, as they say. My hound used to love Mozart - he once growled at Beethoven because he was a sensitive beast, and you could never fool him at high levels.

To take confusion and order it is, of course, the main thing in life; but to do it like Mozart, so that all life afterwards can get itself together before bed and all who hear can clear their own tax out, is the greatest of all triumphs. People tend to take Nobel Prizes, they legacy of the dynamite boy, seriously nowadays; but all anybody needs to know about prizes is that Mozart never won one, except the one beyond politicians, beyond intrigue, beyond argument, beyond death.