I found this book to be a disappointment. The subtitle is Galileo and the Roman Inquisition, yet only one third of the book is actually about this subject and compared to others that I have read I found this treatment to be largely deficient. The treatment of the many subjects covered in the book is very scattered, with many tangential digressions that, in my opinion, while interesting impaired the continuity of the book. Instead of a linear well-ordered presentation, the book rambles from subject to subject and the reader is then left to piece the story together for himself or herself. Some readers, particularly those who do not like ordered histories, may appreciate this approach, but I did not. The epilogue of the book clearly illustrated what I found most annoying about the book. Instead of a discussion of Galileo's life after his trial, in which he built the foundation of physics that Newton built upon, the epilogue contains a discussion of painting. It clearly shows the bias of the book towards art history instead of the history of science, and I wanted more about Galileo's contributions to science.
The first two-thirds of the book deals with Galileo, his work with the telescope and Maffeo Barberni (Pope Urban VIII). The biographical material concerning Galileo is very fragmentary and incomplete. If this is your only source of information about Galileo you would hard pressed to understand why he is often spoken of as the father of physics and he laid the groundwork for Newton. His telescopic investigations are interesting, but are presented in a more coherent manner in many other books (I recommend Galileo's Universe by Maran and Marschall as a much better source for this information). I did find the information on Pope Urban VIII to be very interesting and in this area I did find new information that was not provided in the other Galileo books that I have read. The author paints a more favorable picture of Urban VIII than that of other books, concentrating on his being a patron of the arts.
The focus of the book is on the Galileo's trial. Historians have struggled with two vexing questions, which I feel the book did not address in enough detail. Firstly, why was Pope Urban VIII so angry with Galileo, when it appears that he had encouraged him to write the book that led to the trial. Secondly, why did the trial take place and why was Galileo forced, in effect, to plead guilty. To understand why the Pope was angry one need only look at the way the question of the idea of a stationary earth (supported by the Church because this is what is implied in the bible) is presented versus the new idea of a moving earth and a stationary sun. Most treatments of Galileo's book go to great pains to clearly lay out the form and substance of the book. While Hofstadter's book does discuss the form of the book, it does so in a very fragmentary fashion. For instance, while it mentions that the book is in the form of a dialog, or debate, and it mentions the names of the debaters, it never even mentions the moderator, or the fact that Galileo presents a lot of detailed technical support for the idea of a moving earth. This support answers the many questions raised by the concept of a moving earth (such as why we do not sense the moving earth) and clearly shows this to be a viable, if not necessarily the correct description. Indeed this was one of Galileo's problems - he did too good a job of defending the moving earth idea and a terrible job of defending the church's position. The names of the debaters are another critical aspect of the book, as the supporter of the church's position is named Simplicio, which sounds like simpleton or simple one in English and more importantly it also does in Italian, the language of Galileo's book. Not only is the church's position presented by someone named simpleton, he also acts like one, or at best a rather ineffectual student who is corrected by the teacher who espouses Copernicus's idea that the earth moves around the sun. The idea that the name of the supporter of the church's position was named simpleton is mentioned just once in Hofstadter's book and not discussed, whereas in every other book that I have read on the subject it is discussed at length. Furthermore, the Pope encouraged Galileo to write the book because he expected him to focus on his idea that since God is omnipotent he must not be limited by any idea that Copernicus or anyone else might come up with. Thus, at best the Copernican model should only be thought of a supposition and not a true description of how God chose to organize the universe. Galileo failed to include this idea or to clearly state that the Copernican model was just speculation and should not be thought of as depicting reality. The censors caught these omissions and made Galileo alter the book. However, Galileo put the Pope's idea into the mouth of Simplicio, and then abruptly ended the book by having the supporter of the Copernican model state that, in effect, if this is what the Pope believes we cannot question it. No wonder the Pope was angry! The Pope's idea is discussed in Hofstadter's book, but using the language of logic and in a manner which I found totally confusing. Indeed had I not read other books on Galileo I would not have understood what the Pope was saying. The one new fact that I learned was that the preface and this last part of the book were printed (in the original printing) in a different typeface, clearly showing that they were not part of the original book, but were added to satisfy the church censor.
Galileo included the censor's changes and the book received the church's approval for publication, so why was there a trial? Most historians point of the Pope's anger as the cause. However, because the book was approved, it actually did not play a very significant role in the trial. Instead, the focus was on whether or not Galileo had obeyed a 1616 injunction against teaching that the earth moves. Galileo had proof that he was allowed to discuss this idea, but just not to hold that it was true, and he believed that his book had not held that the idea of a moving earth was definitely correct, especially with the preface that clearly held that this was only a supposition. While technically this might have been true, the nature of the dialog presented in the book clearly showed what he really believed. These things are discussed, but not as clearly as I would have liked.
Given the aforementioned difficulties that I found with the book, why am I giving it as many as three-stars, which according to Amazon's criteria implies that I was neutral concerning the book, i.e., I did not dislike it (2-stars), nor did I like it (4-stars). I am giving the book credit for the many interesting digressions, such as use and the method of torture used in Italian Church inquisitions versus that used in the Spanish Inquisition or in civil trials of the time. (Hofstedter holds that torture was not used by the church in Italy as much as in civil cases or as much as in the Spanish Inquisition and its use in Italy was very restricted.) I also found the discussions of church politics to be interesting, but if you want a highly readable, but more complete discussion of Galileo's life and the trial I recommend Galileo's Daughter by Dava Sobel.