Correction: An earlier version of this review incorrectly said that a gunman killed 10 girls in an Amish school in 2006. Ten girls were shot; five of them died. This version has been corrected.

An Amish girl rides her foot push bike down the road, past a cornfield, as PBS’s cameras got about as close as they could. (Tim Cragg/PBS)

It can be a real problem when the people you’re making a documentary about are forbidden by their religious code from appearing in it.

The Amish of PBS’s beautiful and gently rendered film “The Amish” (airing Tuesday night) are mainly seen in groups, from a distance. When they tell their individual stories, we hear audio only; the camera is not permitted to film them directly or intimately.

So what else are you going to film? Cows? Rolling hills?

Yes, precisely that. Lots of barnyards, much threshing and hay-baling, hands performing kitchen chores, laundry being hung to dry. “The Amish,” written and directed by David Belton, with gorgeous cinematography by Tim Cragg, is as quiet and unassuming as its subject matter. The effect is alluring and beatific.

From its first moments, viewers are put in a contemplative and deliberate frame of mind, as if on an enlightened walk through the fields of the Lord. Along the way, the Amish — and the sociologists and historians who have studied them — have much to teach us, not only about simplicity and basic living, but also about the most elusive happiness of all: the spiritual kind.

Because it’s about the Amish, the film is naturally fascinating. Who hasn’t blown past a horse-drawn buggy on the back roads of Lancaster County, Pa., and wondered: Who are they really? What is it like to live so resolutely apart from the modern world around you? Belton and his crew immersed themselves on the peripheries of Amish communities in Pennsylvania, New York, Indiana and Ohio, staying through the seasons of hardworking harvests and the cold winter and the verdant summer redolent with the Rumspringa urges of the Amish youth.

“The Amish” opens with scenes of the thriving tourism industry in Pennsylvania that created a curious economic co-dependence between the Amish and “the English” (their word for everyone else). Is there some meaning to divine when everyday Americans (and foreigners) become so sentimentally transfixed by Amish ways? Millions of people come to Amish country each year — seeking what? Refuge from a noisy and wired world? A glimpse of what might have been? The picture here is somewhat depressing: Overweight lookie-loos in cargo shorts and flip-flops, lapping up homemade ice cream and furtively snapping iPhone pictures of the Amish at work.

But “The Amish,” part of PBS’s “American Experience” series, is not a tourism brochure. Much of what we learn about the Amish life is fraught with questions, some of them unsettling. If you were to change one or two tiny details about what the Amish believe and practice, would it cease to seem so quaint? Or would it look more like the fundamentalist compound of, say, Warren Jeffs? Is turning the entire world into forbidden fruit really the surest path to a clear conscience? And why is it okay for one community of Amish to carry their lunches in bright plastic Igloo coolers, while another may not?

Though it sometimes drifts into tangents, Belton’s film does an excellent job of unpacking the Amish worldview, as well as our imaginings about the Amish life. It also documents the religion’s function as a litmus test to freedom. The Amish challenged mandatory public schooling (and won) and, in New York, have lately busied themselves protesting building codes that would force them to install fire alarms and automatic sprinklers.

Tracing the Amish story back to the Anabaptist Christians of 16th-century Europe, “The Amish” explores the deep persecution that formed not only the original movement, but also the Amish psyche. Rather than turn them into clamorous religious zealots, the persecution effectively rendered the Amish wary and insular, resolutely set in their ways. In immigrating to the American colonies in the 1700s, Amish settlers found their bucolic bliss among the Pennsylvania Dutch; for a long time they looked and acted like anyone else. They adored the 1800s, until the Industrial Revolution spooked them into drawing more firmly a line that would forever separate their world from that of “progress.” “I’d like to have a camera,” one of the film’s subjects muses to her interviewer. “But it’s not worth it.” (Not worth the value of her own peace.)

No one makes a better case for the comforts and joys of being Amish than the Amish themselves, who speak eloquently and repeatedly of the freedom that comes from being “in the world, but not of it.” They are biding their time diligently, and mindful of their insignificance compared to God’s.

It doesn’t work for everyone. “The Amish” follows people who left the community for various reasons — not because it was strict or abusive, but because they couldn’t resist the idea that the world has more to offer. Others struggle with maintaining their Amish-ness amid a decline in agricultural opportunity. In Indiana, throngs of Amish men now work regular shifts at a factory that makes, of all things, RV campers. The line between “in this world” and “not of it” gets blurrier all the time.

But it also comes into sharp focus. In 2006, when a deranged gunman took over an Amish school and murdered five girls and then killed himself, the stricken Amish community swallowed their rage and forgave him. The Amish can show us a lot more besides how to make a quilt.

The Amish

(two hours) airs Tuesday at 8 p.m.
on WETA and MPT.