I thought of this conversation when I was reviewing Niall Ferguson's biography of Siegmund Warburg for the Washington Post. I felt that Ferguson was being too much the historian, and not enough the writer, when he "splintered" the different aspects of Warburg's life into different chapters, essentially covering the same period of time again and again. While often quite useful for a historical study, I firmly believe that this approach does not make for good writing. It does violence to the organic unity of a life.
Here lies one of the trickiest tasks for a biographer: He must evoke the visceral sense of how a life was lived, how various roles and tasks had to be handled simultaneously, how the pressure of a personal dilemma, for example, was interwoven with professional conflicts.
More than that, the biographer must search for themes, for the underlying unity of a given period of time. This is truly an art. The biographer must provide the illumination shed by her own distinctive mind on a tangle of historical events. Who the subject was as a person, and what these conflicts or developments say about her, must be thought through, illustrated with well-chosen quotes or anecdotes, and supported through the narrative.
In my most recent book, I often tried to set the thematic tone at the outset of each chapter, and demonstrate how that theme emerged through all aspects of Vanderbilt's life. Sometimes I decided upon where to cut the cord of time—where to begin and end chapters—based on the themes I saw clustered together in the various elements of my subject's existence.
Like anything, this can be done badly. Perhaps I did it badly at times. It can be heavy handed, and seem inauthentic to the factual, irreducible flow of events. But, if done well, it is a path toward explaining a life, even as it unfolds it as a single, organically cohesive narrative. One life, one story: it's a handy guide to writing a biography.