Having nothing, the two families take nothing for granted. Least of all, they take no comfort or faith in the blathery talk that an economic recovery is now surging through the land. For these families--one black, one white, both reasonably secure only a year ago but now fearful that the Reagan policies are about to devastate them--the recovery has yet to arrive. The goal for both families, backstopped by little more than inner grit, is to keep from falling further to the bottom, and forget about inching up higher.

Mary Chambers (a pseudonym), 47, divorced and disabled, a former cook and hospital worker with one of four children at home, lives in Gifford, a small all-black rural community on the east coast of central Florida. Two miles north, Arthur and Rachel Monroe (pseudonyms) and their two teen-age children wonder what's ahead. The father was recently laid off after five years of driving a sanitation truck and the mother lost her assembly-line job at Piper Aircraft due to a factory slowdown.

Indian River County, its citrus groves fertile with the country's juiciest oranges and grapefruit, is a contrast of hard times and high times.

Unemployment in July was 16.4 percent, far above the national rate and a point and a half higher than in July 1982. An official of the Economic Opportunity Council, a social program begun in the Johnson administration of the mid-1960s, says she receives nearly 100 appeals a month for emergency help from families that can't make it. Three years ago, the number was about five a month. From two short-term grants totaling $23,000, $1,000 a week is given to unemployed families to help pay their rent, mortgages or utilities.

In contrast, the new rich have established parts of the county as havens of opulence. John Mecom, a Houston oil man and owner of the New Orleans Saints, who train here in August, moors his 163-foot, $12 million yacht in Vero Beach, two miles south of Gifford. Its fuel tanks take 48,000 gallons of diesel. The Miami Herald computed one fill-up to cost $61,440, a sum well above the market value of the Chambers and Monroe homes combined.

Fifteen years ago, when I first came to know some of the families in Gifford, examples of Old South racism and shantytown poverty were easily uncovered. What one local newspaperman called "squalor vignettes" were as ripe for picking as in-season oranges. With no clean drinking water piped in to Gifford, blacks would go to Vero Beach to fill their jugs from spigots on the courthouse lawn, the same spigots from which the dogs of white people drank.

Life in Gifford is not as harsh today. Clean water is available, and many of the low-income social programs set in motion in the 1960s--from public housing to Head Start--have had their positive benefits.

That's what unsettles Mary Chambers. The gains are under threat. She pays out $273 a month for her mortgage, plus more than $50 in utilities. In 1970, she qualified for Social Security disability money, because of a heart condition. Early this year, with the Reagan administration in full charge against suspected deadbeats ripping off the system, Chambers said that local officials ruled she was healthy and able to work.

She is appealing the decision to cut off her $270 disability benefits. Meanwhile she goes month to month on $111 in food stamps.

With Chambers sick and unable to work, the Monroes find themselves in the opposite fix. They are healthy and want to work, but can't. Last month, they were among the lucky who were rescued by an emergency rent check from the Economic Opportunity Council.

In talking with both families--Chambers and her daughter in their small living room and the Monroes on chairs under a tree next to a dirt road fronting their home--I sensed that the American dream was being redefined: Work hard to get ahead is now work hard to get by.

The effort for Chambers is to prove before the courts that what her government had been saying since 1970--that her heart condition entitles her to Social Security benefits--is still true. The Monroes have applied for food stamps. If they can't find jobs, they will seek more emergency funds for the rent.

Though they feel ashamed to be asking strangers for money, these two families' deeper feeling is that the economy may well recover without them. The 16.4 percent unemployment--a conservative estimate--is being accepted as normal. In the economy of the 1980s, the fear--and not only among the poor--is that once you go down, you stay down.