FRANKLY WE DON'T feel a day over 80. But never mind - this is the 100th birthday of The Washington Post. How do you celebrate your 100th birthday? Well, if you are a newspaper, you celebrate it the way you do every other day: with yet another edition of the paper. This can have a bracing, Ponce de Leon effect. Much as well like the wise old head image, it's hard to feel 100 years old - with either the feebleness or the sagacity that implies - when you are meeting a daily deadline, chasing and being chased by the local and national competition and completely recreating your product every day. It's not the kind of routine that leads an institution to age gracefully - or even, in a sense, to age at all.

Still, we know we are 100. There is an abundance of literature and lore to that effect and some of it, we are bound to say, makes instructive reading. We have in mind in particular the evidence that (despite what you may have heard from some politicians in recent year) the contemporary Post is downright ovuncular and benign compared with the product of the good old days. What's that you say about how The Post just doesn't seem as objective as newspaper used to be?We invite your attention to the happy lack of fastidiousness of our ancient and revered founder. Mr. Stilson Hutchins, in this respect. Mr. Hutchins saw fit to let President Hayes be described on this paper's front page as "his fraudulency". And where women's rights were concerned, we are afraid he had a consciousness that couldn't have been raised by the Glomar Explorer. "Those Frantic Females" was the way he headlined a story about the suffragettes.

So forget about that journalistic slippery slope into "lack of objectivity" you keep hearing about. Yes, The Post, like much of the rest of the American press, has its work cut out for it in contriving to be fairer, more accurate, more timely, more dispassionate, more comprehensive and also more of just about everything that is included in the Boy Scout oath. And we take these obligations seriously. Our point is just that sensitive politicians should consider themselves lucky to be living at a time of such - well- journalistic moderation and restraint, if not actual stuffiness.

We consider ourselces lucky, too, and if you will permit us just one sentimental thought we will tell you why. It is because we live and work and thrive in one spectacular city, a city and a region that have made at least a thousand years of progress - racial, social, commercial and political - in the past century. And all the signs for continued forward movement are good. In a fit of unbridled local chauvinism around 90 years ago, this paper editorially explained: "The Post intends to stand for Washinton, Washington interest andWashingtons, first, last, and all the time". Couldn't have put it better ourselves. We endorse the sentiment and hope to abide by it, although we are keenly aware of the difficulty and the challenge: They say the second hundred years are the hardest.