Lincoln's Dreams, by Connie Willis

What do dreams mean? That's a question people have been trying to answer for years, and we really are not any closer to knowing, though Important People are full of Important Ideas.

In this book, one of the characters is having dreams about the Civil War, dreams that seem to mirror the known facts about what Robert E. Lee suffered during the war. So is Annie dreaming Lee's dreams? It seems so, and they are exacerbated by the nearness of the various battlegrounds and historic sites around Washington, D.C. But how can someone living over 100 years after an event be dreaming something that someone else dreamed? Is that even possible? Or is she just nuts?

Interesting structure of the story, a little improbable (even aside from the dreams), but a fascinating plot and theme.