Judi Dench says

From And Furthermore by Judi Dench:

"Sometime I do have a lot of difficulty learning the lines, but the real difficulty is working out why the character says the line, and what is going on between the lines, which is often more important than the line itself.

Before you start to rehearse you are looking at the wood, which is composed of many trees.  You start rehearsing and you are inside the wood; you know that you are in a wood, but you don't know what the trees round you are until you start to recognize them.  Then the moment the audience comes in, it is as if you have been transported away from the wood, and that is when I think the most important part comes in - when you decide which is the straightest way through the wood."

I also learned from this book that:
1) Judi Dench would've been the one singing Memory in CATS, but she sprained her ankle a few weeks out.

2) Judi and just about everyone else from the big British theaters like the National and the RSC seem to love to play practical jokes on each other onstage - changing lines from Shakespeare, saying Russian names when you sneeze (in a Chekhov play), and other assorted hijinks take up a significant amount of this book!