I AM, BY NATURE, a mutterer. This is a fine, old calling learned during a prolonged period of unemployment when I would sit with the old men on a park bench, face the sun, and mutter. The old men would mutter at anything, especially people who passed by, some crossed that fine line between muttering and talking to yourself.

As for me, I do not mutter at people, but I do mutter. More and more I find myself muttering, "The hell it is."

I do that a lot while watching television. Usually, I do it during commercials, at anyone who says some product is new or improved or the finest. My favorite is the one for Grecian Formula Nine, which, in the span of only two weeks, turned my father's hair from just gray to gray with blue highlights. He looked a little like Clark Kent in the old Superman comics - Superman being the only man I ever saw, super or otherwise, who had blue hair.

I also mutter a lot while watching the news. Usually, I mutter back at politicians. I was the first person, for instance, to mutter "the hell it is" when Jimmy Carter declared the energy crisis the moral equivalent of war. Almost anything Jerry Brown says causes me to mutter and so does lots of what I read in the mewspaper. The latest item to provoke my mutter was the explanation offered by William Whalen, director of national parks, when asked why his employees were getting free tickets to the Wolf Trap Farm Park.

"It's our park," said Whalen.

"The hell it is," said Cohen.

It may be unfair to single out Whalen for what is, after all, a pretty co mon attitude in government - federal, state or local. It's hard to find just the right word for it - the correct term - but it is something close to what Jimmy Carter had in mind when he so casually threw haymakers at the entire city of Washington. It's a particular attitude he's talking about, and if you had to find one word for it, it would be "possessiveness."

What that means is that some people in government - Whalen is an example - think of their agency as simply that - theirs. A perfect example of that sort of thing is a parking lot at National Airport which is restricted, the sign says, for congressmen, diplomats and members of the Supreme Court.

What that sign tells you is that the Congress, which after all really runs the place, thinks that its business is more important than your business and that it has a greater right to a government facility than you do. Implicit in this is the message that National, after all, is their airport.

You can find examples of that sort of thing all across America. Almost any police headquarters you can name has parking nearby reserved for the police. This is done because the police think that they - and only they - have a constitutional right to park for free near their place of employment, that they have a greater need to be at police headquarters than you do and, lastly, that the building is, after all theirs. If you don't believe that, just try parking in their space.

In Washington, there are lots of examples of this sort of thing - governmental possessiveness. Mostly, it rears its head in matters having to do with parking since that, more than almost anything else, is the government's most important perk. Whole areas of Capitol Hill, for instance, are daily cleared of cars so that the cars of congressmen and their staff can use the valuable curb space. Just how they're entitled to it is something that's beyond me.

Other examples. In the national parks are idyllic little cabins for the use of idyllic little government VIPs. You cannot use it because it is not yours. It is theirs. At the Supreme Court, recently, the chief justice, Warren Burger, put parts of the building off limits to the press on the mistaken notion that the building was his. It ain't. It's yours.

All of this might sound trivial, but there is something more important here than just parking spaces or hideaway cabins, and the mutterers of the old park bench knew it. They spoke of city hall and how you couldn't fight it, and they thought of government as belonging to someone else: to itself maybe, certainly not to them. They saw it the way a lot of people do now - as a closed entity, a tight-fisted operation which felt its first responsibility was to itself and not to the people it was supposed to serve.

So I guess I will continue to mutter, to talk back to the television set and the newspapers in the morning, and to say to officials like Whalen of National Parks when he says that the park is his, "The hell it is, sir. It's ours."