Remember Trudeaumania? The Canadian prime minister catapulted into office in 1968 has now weathered ten turbulent years and outlasted other Western government leaders--by, time and again, changing his style and approach. Personality (1968), professor (1972), politician (1974); despot, drifter; deep-thinking, combative, indifferent: ""What's he really like?"" Canadian Financial Times correspondent Radwanski repeatedly was asked. This is an overextended answer--diverse perceptions of Pierre Trudeau deployed through 350 pages that amount to neither a full, rounded biography nor, as the author notes, an assessment of ""the Trudeau years."" But, by any accounting, the puzzling P.M. is an exceptional public figure, and in today's ominously divided Canada, the person best equipped--as a pro-federation French Canadian--to preserve national unity. Radwanski is effective on both fronts. Drawing psychological inferences circumspectly, he traces Trudeau's testy, sometimes obstreperous individualism from his youthful pranks (like impersonating a German soldier in rural wartime Quebec) to his early public misbehavior as P.M.--a matter perhaps of challenging ""the latest authority in his life."" After briefly practicing law in the Forties, he held no job, did no sustained work, until he entered politics in 1965; did those years of selective study (Harvard, the Sorbonne, the London School of Economics), shoestring travel, and intermittent commitment (first, to labor's cause in the crucial 1949 asbestos strike) prepare him better to take the large view than to handle the ""practical details of running a country""? Can a self-willed ascetic understand the handicaps of the genuinely deprived? Can a man loath to ask favors expect disinterested help? For these and other suggested reasons, Radwanski concludes that Trudeau has not fulfilled his initial promise; and in becoming more the politician, has become less the frank, refreshing voice of reason. But, reviewing the ups and downs of his administration, he gives Trudeau high marks especially apropos of Quebec: rejecting the ""two nations"" theory, he has borne down equally hard on anglophone prejudice and francophone insularity. And, in giving French Canadians ""a more genuine and equal role in the governance of the nation,"" he has turned the fight against separatism into an unequivocal appeal to the common good. Radwanski's not inconsiderate achievement is to have articulated both the dissonances and the drive.