I want to talk about the experience of reading a book that was adapted into something you've already seen. The sequence matters. When you see the adaptation first, the book fills in depth — you read with faces and voices already assigned, which is sometimes limiting and sometimes enriching. When you read the book first, the adaptation either honors or violates your imagination.

The adaptation I think most about in this context is the BBC television adaptation of Jonathan Strange and Mr Norrell. I'd read the book twice before I watched it. The casting was almost exactly what I'd imagined. The condensation — from 800 pages to six episodes — required brutal choices. The choices were mostly right, which speaks to the quality of both the book and the adaptation.

The one thing the adaptation couldn't reproduce was the footnotes. Which means the adaptation and the novel are companion objects, not substitutes.