A link to an outstanding article on and review of George F. Kennan: An American Life by John Lewis Gaddis.
His fluency in German and Russian, as well as his knowledge of those countries’ histories and literary traditions, combined with a commanding, if contradictory, personality. Kennan was austere yet could also be convivial, playing his guitar at embassy events; pious but given to love affairs (in the management of which he later instructed his son in writing); endlessly introspective and ultimately remote. He was, a critic once charged, “an impressionist, a poet, not an earthling.”
For all these qualities — and perhaps because of them — Kennan was never vouchsafed the opportunity actually to execute his sensitive and farsighted visions at the highest levels of government. And he blighted his career in government by a tendency to recoil from the implications of his own views. The debate in America between idealism and realism, which continues to this day, played itself out inside Kennan’s soul. Though he often expressed doubt about the ability of his fellow Americans to grasp the complexity of his perceptions, he also reflected in his own person a very American ambivalence about the nature and purpose of foreign policy.
Update (2 Dec 2011): From a review of the same book by Frank Costigliola:
Though he captures much of the man’s complexity, Gaddis’s depiction of Kennan is ultimately clipped and flattened. Perhaps the problem is trying to frame within “an American life,” as the subtitle has it, the biography of someone who mused that even his friends did “not know the depth of my estrangement, the depth of my repudiation of the things [the American public] lives by.”17 As compared to the portrait in the biography, the personality revealed in Kennan’s diaries and letters—even the figure who emerges from the transcripts of Gaddis’s interviews—was more irreverent as a collegian, more deeply identified with Russian culture as a fledgling diplomat, more ambivalent about his marriage, more alienated from American life, more inclined to concealment, and more tortured by the limitations of old age. The Kennan of the letters and diaries is far less conventional and more complex and elusive than the person we encounter in Gaddis’s biography.
Update (1 Jan 2012): For another good review of the book, see James Piereson's review at The New Criterion.