I read this book about a thousand years ago, in college, when I was (seriously) studying dance, although this book really is not focused on the dancer.
Sweigard provides really organic philosophies about the human body and its "movement potential" and ways to reach that potential -- both phsycially and mentally. Anyone interested in better body alignment, maximizing physical power and grace, minimizing injury, and the imagery tools necessary to facilitate those outcomes should read this book.
I still incorporate many of these philosophies today and still practice "constructive rest" regularly, even though I don't shake my groove thing anymore.
Brilliant book. Lulu Sweigard was a mind a head of her time. Even if you are not a believer in somatic practices (I myself am cautiously optimistic about its benefits) it is a really insightful book on body/mind practices.