A Canadian looks at Canada; The Canadians, by George Woodcock. Cambridge, Mass.: Harvard University Press.

George Woodcock, the Canadian historian and biographer, has written a pleasing and instructive book about a nation whose character has been shaped by its extraordinary geography.

Canada is the second-biggest country in the world after the Soviet Union, with a population of only about 23 million. Its breadth from Newfoundland in the Atlantic to British Columbia on the PAcific is 4,000 miles. Northward it stretches almost 1,000 miles beyond the Arctic Circle to a point within about 400 miles of the North Pole.

"The great unsettled solitudes still dominate [Canadians'] view of the land and condition their images of themselves," Mr. Woodcock says.

He calls his book "an essay about people rather than politics." But in telling the story of the Canadian people it is impossible to get away from the country's constitutional and political structure. So inevitably Mr. Woodcock has had to touch on the divisive issue of the Quebec separatist movement and its threat to Canadian unity.

He blames overcentralization of the federal government for this threat. And, departing from the generally genial tone of his book, he makes a barbed political judgment of Pierre Trudeau, whose Liberal Party was swept back to power in the recent federal elections after only nine months' rule by the Progressive-Conservative Party.

Mr. Woodcock brands "centralist Trudeau" as "perhaps the leading enemy of a workable Canadian unity" and says Quebec's separatist premier, Rene Levesque, may well be that unity's "greatest friend." He justifies this latter assessment on the grounds that Mr. Levesque "has awakened us to the perils of an artificial constitutional unity that will not take into accounts the various . . . needs and aspirations of Canada's regions."

The stern view of Mr. Trudeau stems, perhaps, from the fact that Mr. Woodcock comes from western Canada, where the Liberal Party and its leader are not popular. But Mr. Woodcock has also lived and worked in eastern Canada, and his intimate knowledge of the country and its history makes him an authoritative spokesman for the regions.

Their vital importance in the search for a solution for Canada's constitutional crisis is an underlying theme of his book. He writes: "Centralization, embodied in the outdated nineteenth-century European concept of the nation-state . . . is alien to the Canadian genius, but the full possibilities of a true federalism based on an awareness of the historic and georaphic realities of Canada's regions have yet to be thoroughly explored."

He sees Canada as consisting essentially of seven regions: Newfoundland; the three Atlantic provinces (Nova Scotia, New Brunswick, and Prince Edward Island); predominantly French-speaking Quebec; Ontario; the three prairie provinces (Manitoba, Saskatchewan, and Alberta); British Columbia; the Northwest Territories and the Yukon (where the native people, Indians and Inuit or Eskimo, predominate and which are still ruled by Ottawa).

In his final chapter, devoted to discussing Canada's "identity crisis," the author quotes Canadian poet Alden Nowlan as saying: "The question is not 'Who are we?' but 'What are we going to make of ourselves?'" Mr. Woodcock concludes: "If we have reached the point of asking such a question, perhaps we have at last found our identity."

"The Canadians" is superbly illustrated with black-and-white drawing, prints, and photographs, which are frequently set in wide margins alongside the script, alternating with thumbnail sketches of famous Canadians. There also are a number of color reproductions of Canadian paintings.

It would be easy to point to some omissions and some flaws. One thing I missed is an overall up-to-date map of Canada. But Mr. Woodcock intended this as an essay (more accurately it is a collection of essays) and not as a detailed history.

On the whole "The Canadians" is a valuable book -- one more from a prolific author who has written almost 50 works on a wide variety of subjects.