recently completed and published a biography of martin luther, a lutheran who somewhat predated dietrich bonhoeffer. [laughter] what's the difference between with writing a biography of a figure like luther and be -- and a book like bonhoeffer's? >> there are far more similarities than i thought i would find. when princeton university press described this series and asked me if i would be a kicker offer of it, it took me about five minutes to sign the contract. it was a new challenge because i didn't know anything like this. the first thing you have to do if you're writing a biography of the book is forget about biological analogies. that is you don't want to say the book was born this way and went through adolescence and all those things. [laughter] they don't do that. but they have careers, and they change in the light of the passage of time. think of almost any book you read 20, 30 years ago and think of its reputation now. think of the vonnegut books and the books that were big in the '60s and '70s if you're old enough to have been around then. very different books now. malcolm muckeridge marsh