To one who recently reached the advanced age of 46, the rapidly approaching prospect of old age is both entrancing and terrorizing.

My children will be grown, my life will once again be my own. That is entracing.

But I am not altogether reassured by some of the elderly people I see around me, who spend a good deal of their extra leisure visiting hospitals, going to the funerals of old friends, and restlessly looking for something to do with idle time.

That't if one is doing relatively well.

Many of the elderly are in nursing homes, those cunning institutions created to make certain that the elderly are not under foot around the house. The prospect that I might end my days in one of the places - staring at walls or ever-blaring television sets - terrifies me, but only slightly more than the prospect of aging itself.

I am also puzzled.

History has delivered at least two conflicting images of old age. There is the image of lost youth, declining power, creeping decay and a final lonely passing on.

There is also the image of a crowning culmination of life, respect and honor, the loving circle of one's grown children with their children, and a peaceful death enhanced by the knowledge that a full and worthy life has been lived. No doubt both images are true. Yet no one has satisfatorily explained to me why some of the aging realize one image and some the other.

One thing now seems certain, however. Slowly but surely we are almost guranteeing that old age will be, if not outright misery (which will be the lot of many), then loneliness, poverty and isolation.

Modern medicine must share part of the blame. It has become increasingly ingenious at keeping poeple alive, but has proven singularly unable to do anything about the kinds of lives people live.

If the gift of the life is another 10 years in a nursing home, is that pure gain? Is life on a machine a benefit?

Or consider the job market.

Perhaps it is reasonable that the elderly should be forced into retirement at a certain age and that youth should be given their chance to take over. But that is a very different matter from the other message our culture also delivers. If one is not a "productive" (that is, a money-making) member of society, then one is a pure liability.

Those familiar complaints, however, do not get to the bottom of the matter. The problem of age for me is summed up in a phrase I have heard people, including the elderly, utter ever since I was a child: "I don't want to be a burden on my children."

What an understandable and yet, at the same time, strange thing to say. It is understandable because the prospect of helplessness and dependency is part of the fearful image of old age.

It is also very strange. Those same children upon whom one does not want to become dependent are the very ones who were for so long dependent upon the parents. If children need parents for 18 or even now 20 years - for their life, their food, their housing, their education - why should it seem so wrong for children to take up the burden of caring for their parents when the latter's time of need and dependency has come?

It seems a matter of simple justice and reciprocity, a point well-recognized by older cultures, which would have found bizarre the notion that parents owe everything to children, but children owe nothing to parents.

The fact that the elderly themselves say they do not want to be dependent upon their children does not remove the moral scandal.

The root of evil is the equally strange notion that everyone should be dependent upon himself alone. It is a heady, but false myth. No one is wholly self-dependent, not as a child, not as an adult, not as an old person.

That we should try to be our own person, have our own ideas and maintain some direction over our own lives is a very different matter from being self sufficient. We need other people, not just because someone has to grow the food we eat, build the houses we live in, or print the books we read, but because we cannot even realize our human potential without the company and pleasure of others. What good is language if we have no one to talk with?

The irony of the insistent demand for self-sufficiency is now apparent. Economically, it is impossible in fact for most people to achieve self-sufficiency. Having given up dependence upon family and kin, we are now dependent upon Social Security, Medicare, or the capricious charity of the state.

Emotionally, it is hardly more possible to be self-sufficient. I have seen all those independent souls sitting listlessly on park benches, desperate for someone to talk with, eager to find someone who cares about them, Who needs that kind of freedom?

We have sought the ideal of independence and given up that of the mutual dependence of the old and the young. We are left, then, with no full, rich and positive vision of old age.

The result is neglect, isolation and meaningless anguish for millions of old people.

If the prospect in the years ahead was only more of the same, that would be sad enough. But the worst is still before us.

The most obvious problem is that the proportion of aged in the population will continue to grow, from 9 percent at present to 11 percent within another 20 years or so. There will, in particular, be a very large increase in the number of those 75 and over, a great proportion of whom will need considerable care and attention if they are to survive.

But will they be allowed to survive? One price to be paid for their survival will be an increasingly expensive invesment of medical resources.

The array of medical miracles which can stave off death is increasing, and so is the cost of those miracles.

Should the elderly have access to incredibly expensive open-heart surgery, or by-pass operations, or round-the-clock medical care? Why, some are now asking, should large sums be invested in research on diseases which afflict primarily older people (cancer, heart disease) rather than on diseases, which impair the lives of younger people (genetic disease, for example)?

These are pertiment and reasonalbe questions, which would arise even if we did not already have a problem about respecting the elderly.

Put in the context, however, of a growing indifference to the elderly, they become ominous.

If the elderly are already unwanted, but still at least grudgingly tolerated, the rising cost of medical care technology may make the next step possible. That step is, in the name of medical scarcity, to began denying aid to the elderly.

Our culture is still not so grotesque that it would act in an openly brutal way. It always needs its moral excuses.

Medical scarcity, rising costs, the needs of youth - they may do very well as those excuses, and all the more cleverly because there is more than a grain of truth in them.

They will not have to be invented. They will be there for the taking.