Ponderous flakes of snow are softly pelting the windows of Lewis Martin's harness shop. Thicker and faster they fall, until the Shenandoah farmlands outside loom vaguely like gray, half-forgotten dreams.

The world is gently closing in on Lewis Martin. Even as he works in the shadows, the leather straps dangling from the dim rafters, it is drifting toward him. His fellow Mennonites, who have farmed the surrounding hills for 200 years and who ride to his shop in black horse-drawn buggies, are feeling it, too. No longer can these reclusive people ignore it:

They are about to run out of farmland.

It is a development that, like much in their pastoral lives, has been slow but sure in the making. For 200 years, they have been splitting up their farms among their many children, seeing their numbers grow, buying out nearby non-Mennonite farmers whenever possible, until the supply of good land has been seriously reduced. A number of their farms are now 30 acres and smaller.

"There's talk that we may have to move elsewhere, find some other part of the country with more room," says Martin, pastor of one of the three conservative Mennonite churches serving about 1,000 people here. "It's just a matter of time."

But when Martin says that, he does not necessarily mean tomorrow or next year--or even this decade. Time for these people, who often take 10 years or more to edge up to a problem, define it, debate it and make a community decision, moves on a different scale. A good estimate, say those here, is that perhaps within the current generation a community decision will be made to send out scouts to travel the country in search of land.

There are already signs that the need for land is stretching this conservative community--not emotionally, but in terms of resources. The price of available farmland is growing steadily, and about the only people who now can afford the land are the old order Mennonites, who have grown wealthy through frugality, not design.

But there are other strains, too, such as those caused by the sheer distances that growing numbers now must travel to maintain contact with the community they value so much. Every Sunday morning, for instance, Menno B. Horst, his wife and three children must ride in their horse-drawn buggy for 45 to 55 minutes to attend church in the austere white meeting house some six miles away.

"When I bought the farm in 1970, I was the furtherest one out at the time," says Horst, a short, stocky 42-year-old man with thick red eyebrows and red hair thinning on top. "People in the church were sayin', 'You're kinda gittin' far away from us, aren't you?' Well, you just gotta git up earlier, and make sure you're keepin' a good horse."

Horst farms 99 1/2 acres on the westernmost edge of the 20-square-mile area west of here, where virtually all of the conservative Mennonite farms are located. His family moved to the Shenandoah Valley from Canada 21 years ago for one reason only: to be with other Mennonites who believe that the old traditions must continue.

"My parents wanted to move," says Horst. "They knew people here that felt the same way 'bout it as they did. My wife's father is from Ohio, the old order settlement there. But it's pretty much gone now, 'cause all of them either bought automobiles or moved here to get away from it."

The community is almost everything to these Mennonites, because it protects them from the relentlessly seductive outside world by isolating them. Even so, they are not arrogant in their faith, seeing themselves as they do as frail, imperfect beings, prone to mistakes. To them, the community is a fragile island. Inexorably, life flows all around them, over them and within them.

The 450 years since their faith was founded in Europe has taught the most conservative among them that they must keep their needs and desires at a minimum if they are to preserve the purity of their faith. Only in that way can the outside world have minimal impact on them.

Accordingly, like their relatives in Pennsylvania, they shun electricity in the home and read by gas and kerosene light because electricity makes them dependent on the outside world. They refuse to buy cars or radios or television sets and they drive horse-drawn buggies for the same reason. They scorn anything other than utilitarian clothing, and their women wear bonnets or prayer coverings.

There are perhaps 4,000 to 5,000 other less traditional Mennonites in Rockingham County. In the eyes of the conservatives, they have given in to the blandishments of the modern world. They drive cars, wear just about whatever kind of clothing they choose, work hand-in-hand with non-Mennonites, attend public schools. They even actively lobby local, state and federal government--just as do non-Mennonites--whenever they feel it is needed to protect their interests.

Raleigh Rhodes, 23, is one of them. He is earning his way through Eastern Mennonite College in nearby Harrisonburg by rising at 5:30 a.m. to race through the countryside in his Volkswagen fastback before morning classes. His job? Artificially inseminating the cows of the farmers--a sizeable number of whom are old order Mennonites.

His mother was born an old order Mennonite, and many of his relatives are strict adherents to the creed. There is much that he finds attractive about their brand of his religion, but he also enjoys the contradictions he says he occasionally runs across. One story he tells is about an old order Mennonite who was trying to decide which of two churches he would attend when his house burned down.

"You know, the old orders don't permit insurance, like fire insurance or health insurance," he says. "Everything is taken care of by the church. So when his house burned down, the congregations of the two churches came over and tore down his old house in a day and a half, I think it was, and then built him that little brick house."

Rhodes laughs. "Now, I don't know that they saw it or would admit it, but I could see that those two churches were almost competing, you know?"

Which church won?

"None of 'em did," Rhodes says, laughing again. "He choose another old order church altogether!"

All of the old order Mennonite farms Rhodes visits this morning have gas lighting peeking through the curtains of their houses--and electric lighting inside the cowsheds. They house the most modern and up-to-date automatic milking machines, too. In the background, almost obscured by the pfftt-put, pfftt-put of the milkers, are the sounds of electric generators.

"They can have electricity in the sheds and use tractors as long as it improves their farming. But the electricity has to come from generators on the farm," he says. "They can't bring it in from the outside."

Martin says that, of the 250 or so conservative Mennonite families, only one or two still use horse-drawn teams to plow their fields. Change usually comes slowly. There is talk, then debate and finally, "if it isn't absolutely forbidden, someone will buy a tractor, say, and then others."

But sometimes the community has acted quickly.

Few if any conservative Mennonites attend school beyond the eighth grade, and almost all of their children now attend one of three schools run by the local churches.

"The real reason we went out and built those schools was because we felt public schools was a bad influence," says Horst. "In the elementary school in Dayton, there was a certain very rowdy boy, not a Mennonite . . . . Came to school with a Playboy magazine and he was showin' it. And it wasn't just one. He got ahold of several issues."

In a year, he says, the Mennonite community had built the schools.

Horst and others do not believe that they can--or even that they should--protect their children from the outside world completely. They believe that, in the end, it must be up to the young adult to decide whether to remain in the community.

"It's just like cattle in a lush cornfield," Horst says. "If they be passin' close, even if they never tasted it, they have a yearnin' for it. I don't think the answer is total nonexposure. The children have to work it out themselves."

During the 1960s, Horst had his brush with the outside world when he had to perform community work as an alternative to being drafted. Like all Mennonites, he is a pacifist.

"Where I was stayin', they always had the radio goin'," he says. "Sometimes I miss that. But, you know, what with the speaker talkin' and certain songs always being played, when your mind's on that, when it's all you think about, then your mind's off your thinkin' about your friends and family, where it should be.

"No, I enjoy other things . . . . I enjoy seein' the first bud out in the spring, the first corn through the ground. Then your crop ripenin'. The children. Now, my second son especially, he's anxious for spring so he can help my wife plant the garden."

"Work," he says finally, "well, work is work whatever it is. It's human nature to test work. You have to learn to like it.

"I got a whole lot of work here, and I expect to die here, too."