The paper "Plato’s Republic Book" is a great example of a philosophy book review. In this section of Plato’s Republic, Socrates discusses the which is to be founded and the nature of the inhabitants found there. He explains the way in which the inhabitants will be encouraged to follow the guidelines he lays out for a successful city in the first half of the book. In order for the system to work, argues Socrates, the city must be governed by philosophers. This idea of a ruler-philosopher is central to Socrates argument and will go on to be constantly re-visited in the rest of the Republic. He, therefore, explains exactly what a philosopher is in this context. This is the main focus of the second part of book 5. In Socrates’ idea of philosophers, they are the only ones who can have complete access to the nature of things, and therefore knowledge. This is because they can comprehend Forms, which is an idea that is central to Platonic thought. Forms are the model behind everything in the world and are responsible for giving everything which is in the world its nature. They are an unchanging, perfect shape of an object. Forms cannot be seen, merely sensed by the mind. Philosophers have access to these forms. This is in contrast with the ‘lovers of sights and sounds’ who love beautiful views and noises but are not able to ‘embrace the nature of the beauty itself.’ They do not have the full understanding of the philosopher and therefore do not comprehend the world as deeply. They, therefore, do not have knowledge. Socrates demonstrates this idea by outlining three groups of existence; things which can be known, things which cannot be known and finally opinions and beliefs. Things which can be known are knowable in a complete way because they are associated with Forms. Even if a beautiful woman grows old and is no longer beautiful, and was only once considered beautiful by opinion anyhow, the Form of beauty still remains even if the woman is changed. This is in contrast to the opinion, which is not the same as knowledge. A person, no matter how convinced they are that they know something, cannot truly know unless they comprehend the Forms. All their false knowledge can, therefore, be reduced to opinion. The ‘lovers of sights and sounds’ think that they know the things which can be known but in fact, this is not the case since they do not comprehend the forms. Instead, they opine everything ‘but have no knowledge of anything they opine’. This is because what they consider to know in fact varies – such as the beauty of a woman – and so anything they claim to know is, in fact, the only opinion. They do not comprehend the unchanging form but merely opine on the changing object before them. They are therefore lovers of opinion rather than lovers of knowledge or ‘philosophers’ in ancient Greek. These, ‘lovers of sights and sounds,’ are therefore unfit to run the country because they cannot fully comprehend the world. Rather, a philosopher should hold the position because he has the requisite knowledge. It is essential for the philosopher to become the ruler and for power and thought to combine, Socrates argues because without this there will never be an end to disruption and unrest in the cities, as nothing will ever be based on knowledge. This idea will be more fully developed in Book 6.