Every animator should write a book.
We'd have hundreds of perspectives on the process. Maybe a supercomputer could process them all and come up with the elusive answer to how it's done. I remember reading a similar thing was done to films resulting in the determination that Eastwood's "Unforgiven" was the best screenplay written.
Nancy Beiman's "Animated Performance" is a personal, professional and historical introduction to the animation process.
Unlike other books by animators (Richard Williams, Tony White, Eric Goldberg, Halas & Whittaker, Preston Blair) this one isn't overloaded with drawing by drawing exercises that show exactly how to draw a scene.
The book explains why before it shows you how. Along with Joseph Gilland's "Elemental Magic" this represents a pedagogic shift in animation instruction -a shift I find welcome. Interesting that both authors were staffers at Disney in the late 1990s. These two books make good companions.
"Animated Performance" doesn't sidetrack itself with too much on techniques outside the author's strength. She's a pencil animator, the book is about pencil animation with passing nods to other media. That's a great strength. Books that try to cover too much ground wind up apologizing for the conflation and doing justice to none.
In the tradition of Thomas & Johnson, Beiman relies on personal connections to films to illustrate points. Like them, she acknowledges the ideas of other artists. Interviews and anecdotes with other artists are woven throughout the book and there's no restraint in letting these artists speak for themselves.
It's top notch primer. In fact, I would recommend first time animation students begin with this text (and Miyazaki's "Starting Point") before proceeding to Tony White or Halas & Whittaker and then Williams. Right there you'd have a solid three year course of study.