"As I write, I don't know what this book is about", p. 203.
I don't really know either, but I don't feel bad about it after reading that.
I learned a lot about random things: real tennis, 16th century Popes and bishop and cardinals, Mexican featherwork, Caravaggio, Cortes. Thanks you google and wikipedia for being there for me as I read. Mostly I guess the book is about various people in the 16th century. Is the tennis game an allegory? I have no idea, I am not good with allegories. What does this book mean? I have no idea.