WHEN STEPHEN CRYSTAL told a friend that he was writing a book about national policy toward the aged, his friend said, "I didn't think there was any." In a sense, there isn't -- and that is the theme of Crystal's scholarly new book. America bases its treatment -- or, more often, non-treatment -- of the aged on myth, misconception, fear, and misunderstanding, turning the notions of retirement, of social "security," of leisure in the "golden years" into a cruel joke.

We can no longer afford to turn our backs on the aged, Crystal says. Demographics alone compel compassion. "Ultimately," he warns, "the aged will include almost all of us," and by "us" he means mostly the postwar baby boomers, today's 30- to 40-year-olds who are an eternal "blip" on the curve of the nation's age distribution. As this population bulge moves, like a rabbit swallowed by a python, inexorably toward old age, our current guarantees of a decent income and decent medical care for the elderly will be all but impossible to meet. And as federal promises become ever more elusive, the population over age 65 will split increasingly into "two worlds" -- the very well-to-do, and the desperately poor.

Crystal sets out, convincingly, to dash some of our most cherished stereotypes about the elderly. He uses a wealth of data to counter myths such as the one that the aged are physically infirm. "With improving health standards, fewer physically debilitating manual jobs, better nutrition, and longer life spans," he writes, " 'the young-old' retiree between 65 and 74 is likely to be as capable of being productive as someone in his late fifties or early sixties was two generations ago." He refutes, too, the stereotype of the aged as lonely: "In 1981, 65 percent of those under 65 believed that loneliness was a very serious problem for most old people, while only 13 percent of the aged found this (problem) very severe for them personally." The once-popular "disengagement theory" (that we naturally and inevitably pull away from social intercourse at life's close) is also discredited, though the theory still forms the backbone of "our expectations about retirement and our overuse of institutions such as nursing homes."

Among the most cherished myths about the elderly -- and, according to Crystal, the most dangerous -- are our myths about the aged in the family. Contrary to popular belief, old people are not dependent on their adult children for money or support. Less than 5 percent of the aged regularly receive money from their adult children -- in fact, "the elderly are twice as likely to report providing financial help to children as to report receiving it!" -- and most do not rely on their extended family members for ongoing support.

When asked, the elderly generally are forceful in insisting on independence from their adult children. And their children, as the prospect of caring for Ma and Pa looms closer, are just as forceful in believing their parents should continue to live on their own. According to Crystal, the myth that the family network still supports the aged is potentially the most damaging, because "the assumption that public benefits for the needy aged merely supplement or displace family help can easily be used to justify cutting back the programs that constitute the floor under economic well-being and access to care for the aged."

Declining fertility rates and that ever-present population blip of the baby boom means that many of our current policies toward the elderly will soon need significant rethinking. Crystal documents the now-familiar crisis ahead for Social Security: when the program began in 1945, there were 50 active workers contributing to Social Security for every retiree drawing an income from it. Today, there are just three active workers for each retiree, and in another 45 years the ratio will drop to two to one. Concludes Crystal, "something will have to give -- much higher payroll taxes, benefit cuts, an advance build-up of the trust fund from its present token level to cover the problem years, or some combination of these. Still, it should be noted that today's benefit levels could be sustained even in the worst coming years if we were willing to pay social security tax rates at the level currently imposed in a number of European countries. . . . The social security ride will never again be almost free, at least not in any of our lifetimes."

It's no wonder that a recent Harris survey found that nearly 70 percent of workers under age 55 expressed "no confidence" in the Social Security system, and more than half the workers surveyed by The New York Times/CBS News said they didn't believe there would be any money left from which they could draw their own Social Security benefits.

In an age of diminishing resources, Crystal projects, the elderly will be left more and more to fend for themselves, depending on private pension programs, savings and investments, and family members for their means of support. As the government pulls back on its commitment to the aged, there will be no middle ground. Persons over 65 will be either well off (those more likely to be under age 75, physically healthy, and connected to spouses, relatives, and other members of the community) or disadvantaged (those more likely to be very old, sick, poor, and alone).

Crystal offers some suggestions to stop this widening gap, but his recommendations are generally uninspired. His prose, too, is uninspired, sprinkled so liberally with numbers and statistics that the mind reels and the eyes glaze over. Still, America's Old Age Crisis is a useful book, and even if its message has been heard before it needs to be heard again and yet again. There is a particular shame, and a particular irony, to our callous treatment of the aged, our quickness to allow a significant group of old people to slip quietly into poverty, isolation, and sickness. Because the aged, as Stephen Crystal reminds us, "are a unique group: they are the one minority to which we all anticipate belonging."