Theme from The World Haunted by Demons Books that promote pseudoscience are often popular and profitable. Books that encourage skepticism are much less marketable (Nickell 106). The underlying theme of the first part of Carl Sagan's book, The Demon-Haunted World: Science as a Candle in the Dark, is that there can be considerable harm if science is not used as a means to observe what is not completely understood. This means that people should study everything objectively and let popular beliefs intervene when drawing their conclusions. In the last part of the book, Sagan emphasizes that education is a tool used too rarely (Sagan 351). Even without stating it directly, Sagan's first theme comes through quite well. He doesn't hide behind the sentences, only poking his head out from time to time, he scrolls past the paragraphs saying "look at me!" This is because Sagan's writing is so vivid and powerful. All he needs to do is add a few comments and his examples are self-explanatory. One of the most obvious places this works is when Sagan writes about medicine and its relationship to science. It describes how medicine made enormous progress until the Middle Ages, when lack of interest in science stopped all progress. There was a century when “no progress was made in any area” (Sagan 17). The disease was endemic. Sagan then writes about how today's medicine has virtually eliminated many once-deadly diseases. Here, Sagan does not need to state his theme, the message is clear; where would we be without the medical advances brought by science? When people stopped using science as a tool to look at the world, chaos reigned. At the beginning of the chapter titled “The Road to Freedom,” Sagan recounts the rise of a young African-American named Frederick Bailey, descended from an illiterate slave in Baltimore. becoming one of the greatest orators of his time. He changed his name to that of a character in Walter Scott's The Lady of the Lake, becoming the one we know as Frederick Douglas (Sagan 353). This chapter and the following chapters show wonderfully how beneficial education can be. Sagan really has strong feelings about the power of knowledge. This is likely because he came from a lower-middle-class family and through hard work became one of the country's most respected scientists (foreword by Sagan).).