This is an older book but is still quite relevant. It has also been famous over the years and required in innumerable college classrooms. The author states early in the text that this is a work of theory, and he provides only antidotal evidence for his assertions. Therefore, his ideas are really to be critiqued and considered rather than cited as even tentative conclusions.
Nevertheless, Hoffer has powerful ideas about human nature and the reasons that individuals are drawn to a mass movement even and perhaps especially if it requires what he calls the “vilification of the self.” What turns a person into a fanatic? This seems to be a question that is worth answering. And at least Hoffer is asking the question and providing some very thoughtful theories.