It was like people returning to their roots. About 300 Afrikaner families gathered on this arid cattle farm in the Groot Marico district of western Transvaal to celebrate the art of making moonshine liquor handed down to them from their voortrekker ancestors who opened up the country 150 years ago.

The voortrekkers made the moonshine not because regular liquor was under prohibition but because none was available in this remote and hostile hinterland into which they trekked in ox-wagons to escape British rule at the Cape of Good Hope.

They gave the name mampoer to the fiery distillate that they boiled out of fermented peaches, apricots, wild berries, the fruit of the prickly pear cactus, or whatever was on hand. When they used grapes they called it witblitz, or white lightning, which was the strongest of all.

It was a tough liquor for a tough frontier people, and it was to become interwoven with Afrikaner folklore. This hillbilly region in particular was made famous by Herman Charles Bosman, a writer of folksy tales that brought out the inner warmth and often unconscious humor of a people whom the world and most other South Africans see largely as stiff-necked racists.

The making of mampoer was in danger of dying out because of laws prohibiting the passing on of distillers' licenses from father to son. The number had dwindled to 109 when the law was changed last year to permit the inheritance of licenses again.

The liquor still cannot be sold or moved off the maker's farm, but the change means that at least the tradition of mampoer will live on.

Saturday's celebration was occasioned by the decision of the mampoer-makers, or stoker as they are called, to form themselves into a guild appropriate to their new status.

They were invited to perform this ceremony here at Koperfontein by its owner, Oom Apie van Staden, a rotund 74-year-old father of 10 who is a connoisseur of mampoer and a stoker himself.

Oom Apie even invited a Cabinet minister, Oom Hendrik Schoeman, the minister of transport, to give the occasion a touch of class.

"Oom," it must be noted, means uncle, and everybody in these parts is called either uncle or aunt as a term of respect. The proper mode of address is in the third person. "Good morning, uncle," says the youngster in short pants at the farm gate. "Will uncle please drive straight up the road and park uncle's car under the black wattles."

They came, many of the "ooms" and "tannies," in Mercedes-Benzes, for the Afrikaner is no longer the underdog in South Africa that he once was. His National Party has been in power for 34 years. It has looked after him well--and he is determined not to let any of that power slip away to the black majority.

Most of the burly men wore baggy shorts and open-necked shirts, but the women came dressed to the nines with bouffant hairdos and high-heeled shoes that had them tottering over the rough ground to Oom Apie's big iron shed when the ceremony was held.

They were a little stiff and formal to begin with, and it took them a little time to unbend. But the warmth of country folk and pioneer stock lies only a sip or two beneath the surface.

So it came to pass that the great mampoer booze-up began with a reading from the Bible and a prayer. Dominee Daniel Jakobs, of the Hervormde Kerk, the sternest of South Africa's three Dutch Reformed churches, quoted from Genesis to warn the assembled stokers of the evils of liquor.

Then he also noted that the Bible is abundant in its approval of the preservation of a people's cultural heritage--and mampoer, after all, is a piece of Afrikaner culture. So the minister pronounced it all right.

The celebrants thus reassured, a band struck up, featuring a concertina and guitar, playing the bouncy waltzes and quicksteps of traditional boeremusiek, the music of the voortrekkers. Barbecue fires flickered to life under the wattles, and in a hut a short distance away some stoker got the furnace going under Oom Apie's big copper still.

Proudly the old uncle watched as the colorless liquid began to drip from a pipe at the bottom of a 44-gallon oil drum filled with water. When the liquor ignited at the touch of a match and poured in a flaming stream to the floor, Oom Apie pronounced it ready to drink.

"Damned healthy stuff," he declared. "I've been drinking it every day for 34 years and I've never seen a doctor, never taken medicine."

He recommended it particularly for toothaches, snake-bites and corns. For the corns, just dab it on with cotton. If necessary, he added, you can also fuel a tractor with it.

Meanwhile, back at the shed, entries rolled in for a competition to choose the champion mampoer-maker.

The variety was as mind-blowing as the liquor. Green, red, yellow and brown bottles. Spirits distilled from every fruit imaginable. Others sweetened and flavored to make them into liqueurs: orange, banana, honey, apple, coffee and aniseed flavors.

A crimson "Cointreau." A thick, white substance was called "mother's milk." Another, made of cream, chocolate and mint with an apricot spirit base, bore a label advising: "shake before pouring."

By evening the place was swinging. The two ministers, Cabinet and religious, had left, taking the last inhibitions with them. Oom Piet van Vuuren's concertina trilled louder as he skipped about the floor in his baggy khaki shorts, and Tant Sannie's shoulder straps came adrift.

The champion stoker turned out to be Oom Daniel Yssel of Ventersdorp, an amiable giant with a Stetson hat.

Oom Daniel was overwhelmed by his success. "Bliksem--bloody hell," he kept muttering as he sat with his family around their barbecue fire.

He had not even entered his best mampoer, he confided, because some dumb judge thought it was burned. In fact he had matured it in an old wine vat.

"My worst mampoer won the prize," he marveled, grinning under the Stetson. "Bloody hell, bloody hell."