Something awesome did happen in America last week and we all know it was not a snowstorm.

Without quite defining it, we know intuitively that this television series called "Roots" was a shared crossing over deep water, a stunning passage in the mass culture of America.

To grasp this, merely consider 30 million American families, nearly half of our population, gathering in their living rooms for eight evenings, children and parents, to watch an eightpart melodrama on our greatest national disgrace. Black people groaning in the hold of the white man's slave ship. This TV set in your living room is a powerful preacher.

Or try to imagine the reasons why this gruesome story, so long suppressed or excluded from our orthodox history, should now enthrall us. What makes the ugly truth so compelling to America's popular audience at this point?

Whatever speculative explanations you may come you with, the fundamental message is the same: Our shared memory has been abruptly altered, broadened to incorporate long-denied realities.

Beyond this blunt acknowledgement, it will take a long time (and probably many arguments, from many different viewpoints) to define the message of "Roots" and its impact on ourselves. In obvious ways, it was a very crude history lesson and critics will enumerate the benign falsehoods and wholesale simplifications. As a sequence of eight dramas, it was better than most TV but still clumsy and blatant, in the manner of TV melodrama.

Low history, bad art. These complaints are still only footnotes, I think, which do not really reduce the social phenomenon of "Roots." It has glorious implications for the future of the nation, an obvious suggestion that the self-enriching process that built the American culture out of many remains alive and inventive. "Roots" is a little frightening, too, as a dramatic example of how our mass mythologies can be defined or altered so effectively, so swiftly by a small number of citizens, the people who control television broadcasting.

The social implications become clearer and more impressive, if one assumes the worst about those TV people, if we assign the most cynical motives to their endeavor. Assume ABC did not yearning to promote racial justice, but from a deep yearning to sell soap and hamburgers to the largest possible audience. Assume also that these TV people know what they're doing, if not as artists or historians, as packagers of massive audiences, as manipulators of images that draw people to their TV sets.

In that sense, the profound social message of the "Roots" phenomenon is contained in this simple fact: White America did not switch to another channel.

For eight nights, white viewers watched coarse, wicked whites inflict cruelty, from rape to maiming, upon peaceable, vulnerable, sensitive blacks. Whites folks joked uneasily among themselves, I can tell you, about this unfamiliar experience. "Maybe tonight's show will turn up a nice white person." And: "Back on the rack, it's time for 'Roots'."

The selfconscious wisecracks suggest that white people were drawn by guilt or a desire for self-flagellaion. Maybe so. Maybe some social scientist will establish this in one of those superscientific polls. In the meantime, I don't think so.

My hunch is that, among white viewers, something nearly the opposite of guilt was going on. Pride is a word too strong (and too ironic, under the circumstances), but I think the effect of "Roots" was, ironically, to make the story of slavery, the truth about it, accessible for white Americans for the first time. Yes, this TV series, so artfully put together, allows - even forces - white people to look upon slavery-and-freedom as their story too. Yes, even their triumph.

That possibility migh rankle some black people who, after all, have tried for generations to get white Americans to focus on the black memory of our history. It's a bit much to suggest that white folks are now prepared to embrace it as their own.

Still, I think that roughly describes what happened last week. For one hundred years, for actually much longer, white Americans have always heard this story told in terms of their own moral redemption. "Uncle Tom's Cabin" established the literary frame: good white folks struggling with evil white folks over the fate of simple, hapless black creatures, idealized beyond recognition as human beings.

That mythology dominated virtually all racial questions until quite recently in our history. It was, of course, enormously satisfying for whites and, as a practical matter, it provided the political dynamic by which the black minority could lever change from the majority. As social mythology, it had its uses. But, on a gut level, people on both sides of these racial differences began slowly to recognize that it is a terribly immature basis for the mutual future, a scheme of values that reinforced racial hierarchy even as it sought to break it down.

Now this TV series called "Roots" trampled the old mythology into the dust, relentlessly tore it up. The first six shows offered a series of white characters who might "do good" for the black folk - the conscience stricken ship captain, the gentle plantation owner, the master's daughter who taught Kizzy to read - and each became a creature of treachery, betraying friendship, inflicting random pain, tearing away Kunta Kinte's heritage.

If the white audience felt a bit giddy, it was an eccentric form of suspense - they kept waiting unconsciously for the white hero to emerge. After all, for generations, this has been the familiar dramatic convention for us and, especially on television, we expect the conventions to be honored. This time, each potential white hero (and heroine) became in turn a part of the evil.

Finally, in Part Seven, there emerged a pale substitute (pardon the expression) but it is not what the white audience has been waiting for. The white sharecropper, "Old George," and his wife are less than heroic - they are incompetent, dependent grateful for the aid the black slaves so freely offer.

In fact, "Old George" is a neat mirror image of that black stereotype from the old mythology - a helpless creature, good-hearted but none too bright, willing to learn, gushingly grateful for the good that is done for him. In short, not very believable.

So what kept so many white people at their sets? Why didn't they switch to something more satisfying on another channel? For one thing, "Roots" was exciting, with plenty of television's bread-and-butter - violence. The other networks, if you noticed, were scheduling all sorts of blood-and-gore in competition, trying to break up that huge audience watching ABC, but "Roots" promised the most exciting kind of violence - racial and sexual violence.

In the process, without any special controversy,the series introduced a number of once taboo images to national television, in vivd terms. Half-naked women. Black seduction. White-on-black rape. These racial-sexual motifs have always been powerful theater and, based on the success of "Roots," you can be sure the TV metworks will do more of them, until perhaps familiarity renders them as stale as other TV themes.

Even so, I think the mature sex and racial violence was a secondary attraction to something much more important that "Roots" was doing. For these programs managed to cast the black story of slavery in totally familiar images - comfortable images that white people could recognize and identify whith. So, during the course of eight programs, bombarded with evil white characters, any sensible white viewer identified with the familiar heroes - the black heroes.

Kunta Kinte's village was portrayed as a pristine Eden where natural man flourished before the invasion of civilization. This is a very old dream, of course, going back to Rousseau, and white Americans have been it often themselves - in the sympathetic movies about American Indians.

The young black warrior even seemed at times to talk like our mythical version of the Indian - an expressive language of natural imagery, rich in noble abstractions like courage and honor.

Torn away from his Eden, the black warrior struggles virtuously in another familiar mode. He and his kin are the classic pioneer family determined to be free and to survive. Instead of battling the cruel elements of nature and hostile Indians, they must struggle against wicked white men and the institution of slavery.

In every chapter, those familiar American qualities reverberate so strongly in the story, that racial differences become less and less important and another message - more conventional and satisfying for everyone - becomes the powerful theme.

This is the American story, "Roots" proclaim, in every qualitative dimension. This story of slaves struggling for freedom is the orthodox story of American values. Their virtues - courage, honor, family, mercy - are the American virtues, the ones we need to believe in as Americans. In short, the dramatic marvel of "Roots" is that it allows white Americans to watch that terrible racial history and instead of consuming guilt, they are encouraged to say to themselves - hey - that's my story too.

The conclusion of the series was so blatant in making this point, it almost became a parody. The black families were "heading west" in a wagon train to freedom - the familiar westward image that still dominates our imagination. The last dramatic scene of those ex-slaves showed them gathered on a green hillside in their new Eden, thanking God for their deliverance. They became "new people," like every pioneer, never mind that the West in this case was Tennessee.

So one might say that the TV craftsmen were providing a clever substitution - destroying the long-familiar moral framework through which whites have always looked at slavery and other racial questions, replacing it with comfortable images that are totally familiar to all Americans. In that sense, "Roots" is the direct descendant of a thousand Hollywood movies and 10,000 TV shows, the homogenized pop culture that idealizes our lives, our society.

The final montage of family snapshots, which shows the subsequent generations of Alex Haley's family, is outside the drama - and perhaps the most controversial distortion of history. It ends with Haley himself, a national literary hero now and, as every viewer knows, a very rich man.

The implicit message is, of course, that the American dream works for blacks too. Every child can make it to the top. That is a fundamental article of faith and an important one for all of us. But those rapid snapshots blur over 100 years of bitter history rather easily, erasing for mythology's sake the truth of that long, slow struggle toward racial equality.

"Roots" might have ended with a more troubling message for us. It might have suggested, as so many viewers noted for themselves, that many vestiges of the dreadful past are still evident in this American society, expressed indirectly in custom, legal process, economic status. That might have been a more authentic reporting of our shared racial history but, to be fair, TV is not a historian. It packages audiences by manufacturing popular myths.

Some people may regard all this as frivolous, but it is the most serious event one can imagine. The beginning of genuine racial equality must surely involve white people, against all their training, choosing black heroes.