I was honored to attend his centennial celebrations four years ago, and was never before or since in a room with such distinguished company.
Rafe Champion has written a fitting brief celebration of Barzun's work, here.
I enjoyed especially Champion's quoting from an interview Barzun gave to a reporter from the Austin Chronicle. The reporter remarked that Barzun had been in close working academic relationships with a lot of Marxists during the 1930s, but had never shown any enthusiasm for Marxism himself, nor had he ever taken up arms against it, identifying himself as an anti-Marxist. The exchange runs thus:
My own sense of Barzun's politics is that he has a fondness for various pre-Marxist sorts of socialism (what Marxists call the "utopian" sorts) and that he blames Marxism and its materialistic emphasis for having cut short that promising line of thought. Likewise with contemporary biology. He identifies with pre-Darwinian notions of evolution and, here too, sees Darwinian notions as too mechanistic and a threat to more vital conceptions of life.
Anyway, if I'm right to think of Barzun as a sort of Proudhonist politically, it explains how he has admirers of both right and left. When his writings touch on politics, there is the air of an emigrant's nostalgia that appeals to the right, but the Proudhonist idealism comes through and appeals more to the left.