What is the author's tone in Theatre of the Oppressed by Augusto Boal?

Boal's work is not an objective study, though its tone often seems outwardly objective. Instead, the book is a view of theater through the lens of Marxism, and particularly Boal's own brand of Marxism. Boal's presentation is colored by a perspective of the world that is defined by social classes warring with each other and the need to educate the people to prepare for a Marxist revolution. He is openly critical of the United States and of the bourgeois, which he classes as oppressors due to their social role, despite any individual propensities. Where he agrees or disagrees, he inserts his opinion, writing primarily a work of personal opinion and argumentation. He is presenting evidence for his arguments, not presenting mere historical fact.