Advances often do jibe with what a book earns in its lifetime, and there may be something to that.

But I'm curious about whether that was a U.K. or U.S. publisher. U.K. advances traditionally have been more rational--and therefore lower--than in the U.S., and that view seems more likely to have been true there than here.

Another factor that's come into play in recent years in the U.S.: Advances have become a financial arms race among publishers to land top authors. They're paying vast sums to sum to haul in or retain big names they'd otherwise lose. What they pay for a book may have less to do with what they think that book will earn over its lifetime than with how they see an author's long-term value to the firm.