Social and political epochs rarely end precisely on schedules provided by calendars. Many historians date the end of Europe's 19th century to 1914 and the outbreak of World War I. What we call"The Sixties" in the United States, with its ethos of reform and protest, ended with Richard Nixon's landslide re-election in 1972 and the winding down of the Vietnam War.

In the same way, the outcome of this year's election means that 2009 will, finally, mark the beginning of the 21st century. It comes as we face parlous economic conditions and a slew of new threats. Nonetheless, we should view this as an opportunity to embrace the words of one of Barack Obama's favorite presidents."As our case is new, so we must think anew, and act anew," Abraham Lincoln declared in 1862."We must disenthrall ourselves, and then we shall save our country."

For all the chatter about the world changing decisively after the terrorist attacks of Sept. 11, 2001, our reaction to the attacks was conditioned by 20th-century assumptions.

[Question] How do you think your work compares to the work of the great 19th century historians, when pretty much all history was popular history? Has your work differed from theirs? Have you been influenced by the trends of 20th cent history — social history, micro history, the use of statistical methods?

Brands: I have found the use of statistical methods, to pick up on the last item you mentioned, to be very helpful — as long as other people do it.

[Question] And you have a masters in math, which most historians probably don't.

Brands: Frankly, I like my math untainted by connections to the real world. Statistical history can be very revealing, but it is such hard work and, honestly, there's just a lot of really boring stuff that goes into that and though I'm delighted that it's done, I'm really delighted that other people are doing it.

When I did a book on Rosa Parks, I thought I was really going to get grassroots with it and interview everybody in Montgomery. And I started going into Baptist churches and talking to people There were only something like 13 people on the bus that December 1, 1955, and I found, like, 25 of them on my first day! (Laughter.) It's like, 'Well, I was on the bus, I was on the bus" — half of Montgomery was on the bus! So you got to watch that with oral history, because everybody wants to inflate their connections to greatness.

No modern American president would repeat the fiscal mistake of 1932, in which the federal government tried to balance its budget in the face of a severe recession. The Obama administration will put deficit concerns on hold while it fights the economic crisis.

But even as Washington tries to rescue the economy, the nation will be reeling from the actions of 50 Herbert Hoovers — state governors who are slashing spending in a time of recession, often at the expense both of their most vulnerable constituents and of the nation’s economic future.