I'm not the target audience for this book, never having gotten into acting. But I still found it interesting.
The first part is an overview of how this form of acting evolved and was performed, being very popular for centuries, and how the masks would perform within their scenarios.
The second part is an overview of the "masks" -- that is, the rigid character types that had to improvise their actions within the mask's bounds. The basic categories were the zanni -- the servant class -- the young idiot in love (mostly with being in love), and the old men who blocked the romance.
The third discusses twentieth-century revivals, and wasn't of much interest to me.
There was an appendix about the right way to make masks, too.