Lord, what gloom and doom we've had around the old homestead, lo these past couple of years, as Susan Hartt Yardley, filled with apprehension, creaked and groaned toward her 40th birthday. In the morning she'd moan, "My life has been a waste." In the evening she'd cry, "More than halfway there, and what's to show for it?" Gnashed teeth littered the carpets, shredded hair festered in the cupboards. Woe was we.

Well, last weekend the dreaded event came and went, and the Republic still stands--though Sue, exhausted by revelry, barely totters. On the theory that you're only going to be 40 once and you'd better make the most of it, I hauled out the brass bands and calliopes: close friends to cheer her, the National Aquarium and Harborplace, the Mozart piano concerti (all 26 of them), a mailbag full of cards from admirers far and near--all of this climaxed by a surprise party that really was a surprise.

It was a huge success, and a vivid demonstration of the curative powers of love and hilarity, but I had best admit that it was icing on the cake. If Sue sailed into her 41st year with something approximating serenity, it had much less to do with the divertissements I dished out than with her own discovery, arrived at through grinding but instructive experience, that 40 is not an end but a beginning. It is in fact, I would argue, the time of one's life.

The pleasures of turning 40 are too readily and condescendingly dismissed in this nation where youth is cherished, where whole industries worship at the shrine of the "18-to-35 market." The problem is further compounded by pop-journalists of the Gail Sheehy school telling us that life is full of "passages" and that we all must wrestle with "mid-life crises" and that growing older is, when you get right down to it, hell--and that turning 40 is just the first step toward the graveyard.

I suppose it is, in the sense that at 40 you start to get your first real taste of the rack and ruin that time exacts: back trouble in Sue's case, gum trouble in mine. That there will be more doctors and dentists in our lives in the years to come than there were in the years past is a virtual certainty, and not on the whole a pleasing one. It gave me no joy, during the snows of January, to spend a week in something approximating agony after helping a motorist push her car out of a patch of ice; the dawning awareness that one cannot do at 40 what one could at 35 is not calculated to get laughs.

Yet there is no getting around these treats; they come with the territory, which is called life, a central fact of which is death. You can scream and moan about the inevitable, or you can accept it and get about the business at hand. Shakespeare, as usual, was right: "Of all the wonders that I yet have heard,/ It seems to me most strange that men should fear;/ Seeing that death, a necessary end,/ Will come when it will come." It is one ailment for which the miracle-makers of science have yet to invent a cure and, that being the case, why waste time fretting over it?

Instead, it says here, seize the day--and 40, it also says here, is the day when life really starts to take on meaning. Consider, if you will, the case of Susan Hartt Yardley. By the age of 39 she had compiled a re'sume' that bore a striking resemblance to the Manhattan telephone directory: Seven jobs in two decades, plus a year as a free-lance--eight shots at the brass ring, and not one of them a winner. All in their different ways were good jobs, all provided rewards (though some of those rewards were mighty small), all introduced her to friends she treasures--yet the sum of them seemed less to her than its parts. Where, she wondered, had that laundry-list re'sume' pointed her? What, if anything, had she accomplished? Did any of this have any meaning?

Good questions, all of them--and tough ones. Sooner or later anyone who is bright and ambitious and eager to leave a mark on the world is bound to ask them, and more often than not the answers are depressing. One of the things that most of us learn around or about that 40th birthday is that we are not going to be what we once dreamed we were, that to an unappealing degree life is an unappetizing sandwich of which we are forced each day to take another bite. Show me a person who still believes at age 40 that life is going to give him everything he thinks he has coming to him, and I'll show you a fool. Disappointment lies in wait for all of us.

Yet over the last several months Sue, who has come to accept if not to like these hard home truths, has looked at the 20 years she'd thought she'd wasted and has discovered that, once again, Shakespeare was right: The past is prologue. What she spent those 20 years doing, she now realizes, was learning, building up a body of experience the sum of which indeed is greater than the whole of its parts. As she turns 40 she also marks her three-month anniversary in a new job that is opening new worlds to her--worlds she could not hope to reach, much less conquer, without all that experience she accumulated over all those hard and seemingly unrewarding years.

Forty is when we start to cash in our chips. We've gone through the joys of childhood, the agonies of adolescence, the tests and experiments of young adulthood, the first hot flashes of maturity; we've had our initiations and our surprises; we've learned, through experience, what our minds and bodies can do for us, what they cannot; we've gained a firmer sense of what is possible in our lives and what is not. We've done all of this, learned all of these lessons--and we're still young. Terminal rot has not yet set in; senility is not right around the corner. We have the physical and mental energy to take all the lessons we've learned and make something real out of them; we have the knowledge, the strength--and the time--to do the job, whatever it may be, honorably and well.

So it was that on Sue's birthday I thought back to the fall of 1979, when, shortly after turning 40, I made jocular reference to that "lugubrious milestone" in a letter to a wise man, himself then just turned 70, who has played an incalculable and wholly beneficial role in my life. As usual, he came through for me. In his reply he observed:

"In passing, I should say that the forties, in my experience, are not a 'lugubrious milestone,' providing you know roughly where you are going, and who is going with you. With these two important qualifications, these can be glorious years. It is your 60th, not your 40th or 50th or 70th, you have to worry about. Because then for the first time, you begin to see the shadows."

Small wonder then that there was joy over the weekend in our little corner of Baltimore. Not merely were there friends and gifts and food and wine, but there was a secure knowledge that Sue is heading in the right direction in the right company. And the shadows are two whole decades away--two decades in which to set the world on fire.