She explains how in the modern world we have separated science, magic, and religion. In ancient Egypt these three were all one thing. We can only hope to understand the Egyptians if we can try, even imperfectly, to understand how they perceived the world.
The book uses a very conversational tone. It isn't meant to be a scientific treatise, but calls on all the author's years of research. I like how Mertz will say we do or don't know something. Or that we can or can't hope to understand something else, where the information is lost. This book is definitely worth reading.