THE FIRST reactions to the Quebec referendum are, on the whole, heartening. They acknowledge that the people who voted against separation from the rest of Canada were not voting for the status quo. Throughout the campaign, the forces of national unity promised that, if they prevailed, constitutional reform would follow. "Now that we have reaffirmed our will to live together," said Canada's Prime Minister Pierre Elliott Trudeau, "we must apply ourselves without delay to the task of rebuilding our home to conform to the present needs of the Canadian family."

That means more discretion and more power to the provinces -- already far stronger, in relation to federal authority, than American state governments. In the United States, the trend is toward tighter national centralization and uniformity of social policy. In Canada, the trend is running the other way.

There has always been more than language to the friction between French and English Canada. Quebec is overwhelmingly Catholic, and until very recently either rural or blue-collar. This puts Quebec at a considerable distance from the Prostestant and middle-class views that prevail in Ontario and the West. Past attempts at constitutional reform have all hit that same rock and sunk. But recently several western provinces have been at odds with Ottawa on other matters of their own, and Quebec's demands for greater latitude in provincial affairs now draws a new degree of support from English-speaking provinces.

Constitutional reform can help, and yet it can't entirely resolve the basic language issue. That's the grievance of young French-speaking Canadians, on their way up in the world, who know that above a certain rank in business and the professions, that world generally speaks English. Those who do not speak it fluently, even in their own cosmopolitan city of Montreal, may well suffer severe handicaps in their careers.

Why did the referendum fail? Clearly, most Quebec voters assumed that sovereignty would carry a high economic price. The idea of economic union with a politically separate rest-of-Canada never looked like a good bet. Perhaps there was also recognition that since most of North America speaks no French, pushing Quebec's language laws beyond a certain point could only increase the new country's isolation. Quebec wants a separate culture, but not an isolated one.

The American interest in Quebec is in its economic growth and stability. Neither seemed likely to be growth and stability. Neither seemed likely to be served well by Quebec's departure from the Canadian federation. But growth and stability now depend on those political leaders who urged Quebec to vote "non." On their response to the deeply felt sense of social difference that lay behind the referendum depends whether the issue of separatism has now finally been put to rest.