It should never be forgot that the Nation's Capital lives chiefly on non-news, and I do not say this is good; merely that people are more concerned with their own enthusiasms than with great and high matters.

The talk of presidential safety (blocking Pennsylvania Avenue by the White House) is on every tongue. That is because everybody is interested in traffic, not because they care much about the White House, figuring we already pay enough for the president's guards.

The sensible thing would be to move the president out of the capital, flying him in for major receptions. The rest he can do by phone, or people can fly out to see him in Provo, Utah, or some other safe place. Since we are not going to do anything really sensible like this, it is only natural we should be more concerned with getting down Pennsylvania Avenue than with somebody's passing whim about security.

And as I look over the past week I see several things that fairly absorbed me but which are not news. Many of them raise questions of "comparable worth," and while you cannot compare apples and oranges, you can and you must decide such grave matters as the entertainment dollar, let the apples and oranges fly as they may.

For five bucks I entered a concert by the Capitol Hill Choral Society, which nobody has ever heard of and whose concerts have never been reviewed, so it was a considerable risk. They performed the Mass in A-flat (Schubert) in the handsome auditorium of the Riverside Baptist Church, which I also had not heard of, with a chorus of 40 and an orchestra of 20. A soprano, Linda Kipps, was particularly engaging in a voice that will doubtless be increasingly heard in concerts about town. There was a post between me and the brass, so I assumed there was no brass required, and when the trumpet and trombones entered I was surprised and (a simian heritage) peered around the post and sure enough, there the trumpet and trombone guys were. Think I rather alarmed them leaning into the aisle to see round the pier, but no matter. These musicians gave intense pleasure.

I liked the music far better than that of "Amadeus," a movie I was forced to see and which reminded me of a cantaloupe six days past prime. And the damned thing cost as much as the Mass in A-flat, speaking of nerve.

Then I met an authority on the bear. Not at this concert, but elsewhere in town. Charles Jonkel lectured to the bear department of the National Zoo. He is an authority on such odd things as the Teddy-Bear Syndrome, by which people conclude wild bears are sweet before the bears eat them. It is the bears' misfortune to have evolved to a pattern of small litters, often no more than two, which works fine as long as the habitat is unrestricted. Few things bother big bears. But with the natural range shrinking along with land development by humans, the bear is not so well fixed. Cockroaches and rabbits are perhaps better adapted to our nation now. He is going to send me more stuff about bears, so I shall come at last to a sound view of the grizzly today -- a vexing question, though bears are news only if Teddy Roosevelt shoots them or if they eat Margaret Heckler.

I have also spent an afternoon of non-news with John Stone and Craig Tufts at the National Wildlife Federation, who introduced me to the idea of a box for bats. I had not previously known that you can attract bats to your garden by building suitable boxes for them, or even that they were desirable beasts to have around the house. Bats rarely carry disease, they said. I thought they all had rabies and would bite the hound. This new perspective has given me much to think of. Also I did not know you can put corn in a washtub of water and attract wild mallards. They are going to get back to me on rats who arrive unbidden at the feast for mallards, finches and everybody else. They hope President Reagan will fix up the White House garden as a Backyard Wildlife Habitat. The main thing they still need there is a brush pile, apparently.

In the old days anybody could drop in at the White House to call on President Taft or Lincoln, but that was long ago. Now you get buzzed just to enter the Capitol, and it is increasingly that way all over the world. Necessary but sad.

This week Ambassador and Mrs. Fein had some people over to see flowers at the Netherlands Embassy. Formerly when they flew beautiful flowers from Holland, the public was invited and that was nice. It is no longer possible, any more than it is possible to just wander in off the street to visit this newspaper or any government building. One of the vases had a mass of blooms the size of a Volkswagen, and I never saw such an assortment of gerberas, tulips, lilacs, freesias, gloriosas and so forth, all forced for early bloom in Holland and flown here without a torn petal.

The Feins have a Yorkshire terrier, Kidogo (an African name meaning small beast, though one does not always associate Yorkies with Africa) who has a plastic hip implant. He is not supposed to jump on the white brocade chairs. He is supposed to wait for the Feins to lift him. He jumps up anyway and the Feins are resigned. He has never been stepped on, the ambassador said, though always present at receptions. I have thought a lot about that dog. They have royal marines at the door now and they salute you. For all they know, you're secretary of state or something. I believe their true purpose is to shoot you if you step on the dog.

I used to feel guilty when I reviewed a week and saw what had occupied my thoughts, when it wasn't Mayor Barry or something. But now I think it's all right to think about the Dutch dog and the bats and the chorus and other stuff that you never read about.

Much real news begins to unravel, anyway, when you focus on it. Looking at the weather forecast today I see that the high the next few days will be "from the 40s to the 70s." The trendy weather bureau has gone in for free choice. A lot of news is like that: it doesn't really mean a damned thing. A bat box, on the other hand, would be as good as a new Aeolian harp.