John Lukacs calls "George Kennan: A Study of Character" (Yale University Press, 224 pages, $26) a "biographical study," noting that a full-fledged biography has yet to be written. Mr. Lukacs ranks Kennan above Henry Adams as a historian and autobiographer and above Ernest Hemingway as a writer about Europe. Kennan emerges, toward the end of this impassioned work, as the conscience of his country.

Although Kennan (1904–2005) is best known as the author of the famous "X" article in Foreign Affairs that formed the basis of America's Cold War "containment" policy, his diaries alone (spanning more than 70 years) have no equal, Mr. Lukacs suggests, as American writing that recaptures history in the making, especially in Germany, where Kennan, a foreign service officer, was stationed in 1927, 1928–1931, and 1939–1941.

Profound respect for Kennan the man and the writer is writ large on every page of this crystalline book, which is a kind of throwback to the 18th century, when the term "character" meant a good deal more than it does today. Life may be unpredictable and ever changing, but character "changes hardly or not at all," Mr. Lukacs asserts. "And by ‘character' I mean his conscious decisions, choices, acts and words, but nothing of his — so-called — subconscious; that is, no attribution of psychoanalytic categories, no ham-handed projections or propositions of secret or hidden motives."

Mr. Kennan's character consisted of certain lifelong principles: Liberal democracies should be viewed with as much concern as dictatorships; the major defining event of the 20th century was World War I, not the Russian Revolution; diplomacy is nearly always a better course of action than intervening in the internal affairs of other nations.

What were the practical consequences of Mr. Kennan's principles? He objected, for example, to much of what passed for American anti-Communism because it was hysterical and ignorant. Stalin should be viewed as a Russian tyrant who had certain national goals, not as an international revolutionary who wanted to take over the world. When Kennan argued that Soviet communism had to be contained, he viewed the USSR as pursuing tsarist goals: dominating Eastern and Central Europe. In the long run — as Kennan predicted as early as the 1940s — the Soviets would not be able to hold onto Eastern Europe, let alone the rest of the world. So much of the American anti-communist talk was puerile, he concluded, especially when coupled with "national self-adulation."

Kennan supported the Korean War because he felt the North Koreans had to be pushed back to the 38th parallel. But he opposed the war in Vietnam, and though Mr. Lukacs does not say much about Kennan's view of later wars, especially the current one in Iraq, to divine Kennan's attitude is not difficult. He called our current president "profoundly superficial," a judgment Mr. Lukacs tacitly affirms when he quotes John Adams: "We are friends of liberty all over the world; but we do not go abroad in search of monsters to destroy." Mr. Lukacs also admires another Kennan zinger about the "curious law which so often makes Americans, inveterately conservative at home, the partisans of radical change everywhere else."

Mr. Lukacs venerates Kennan, but he also faults him, noting that Kennan was spectacularly wrong when he argued America and Britain should not ally themselves with Stalin after Hitler invaded the Soviet Union. Similarly, Kennan's "distaste for democracy," Mr. Lukacs points out, is a "problem that his biographers must not dismiss or ignore." Indeed, Kennan's disdain for this country's domestic politics surely is one reason many of his prescient views went unheeded. Mr. Lukacs never makes that connection. He notes, instead, how tireless Kennan was as a writer and public speaker and how so many of his books and articles have stood the test of time.

Why then have they not received the attention Mr. Lukacs believes they deserve? In my view, Kennan was constitutionally unfit to submit himself to the daily grind of politics, where he might have been able to slowly and painfully shift the thinking of decision makers his way. How could he cajole congressmen when he had nothing but contempt for most of them? He derided Dean Acheson for overselling the Cold War, but Acheson understood that he could not hold himself above politics.

Was Kennan's estrangement from domestic politics a failure of character? This is a question I wish Mr. Lukacs had addressed. Or is it a matter of — dare I mention the vile word? — psychology? Surely Kennan's biographers will need to probe precisely that sensitive point: that node where character and personality intersect. ( )