things blackened and changed.”

Montag is himself an instrument of government policy.  Bradbury’s depiction of a dystopian society in which possession of books is a crime punishable by the burning of one’s home places those who administer that punishment in an exalted position.  Bradbury’s society enlists firemen for the purpose of executing a totalitarian policy intended to ensure a compliant and ignorant population.  As Fahrenheit 451progresses, however, especially after meeting 17-year-old Clarisse and Professor Faber, the latter the repository of historical knowledge and understanding regarding the government’s ban on books, his views both on the government and on his role in enforcing immoral edicts begins to evolve.  This evolution occurs prior to his encounters with Professor Faber; it is his conversations with Clarisse and the emotional emptiness he increasingly feels towards both his job and his wife that open the door to a reexamination of his life.  As Bradbury’s protagonist reflects on his job and on the laws he is paid to enforce, his doubt about both assume a more prominent place in his demeanor.  During a serious lapse in judgment – questioning the status quo before his superior, Captain Beatty – Montag recalls one of Clarisse’s comments:

“Montag hesitated, ‘Was-was it always like this? The firehouse, our work? I mean, well, once upon a time...’

‘Once upon a time!’ Beatty said. ‘What kind of talk is THAT?’

Fool, thought Montag to himself, you'll give it away. At the last fire, a book of fairy tales, he'd glanced at a single line. ‘I mean,’ he said, ‘in the old days, before homes were completely fireproofed.’ Suddenly it seemed a much younger voice was speaking for him. He opened his mouth and it was Clarisse McClellan saying, ‘Didn't firemen prevent fires rather than stoke them up and get them going?’"

Montag begins to view fire not as an instrument of good, but of evil.  The burning of books and of homes takes on a more sinister connotation in his mind, and he begins to equate fire with immorality.  But his evolution is not yet complete.  Fire is an inanimate object.  It is neither inherently good nor evil; its value resides in the purpose to which it is put.  Later in the novel, following Faber’s advice, Montag flees to the river to escape this totalitarian society and to seek redemption.  His encounter with the other people who fled that system before him allows him to view fire again in a positive, if more humane light:  fire as a source of warmth and of light.  As Fahrenheit 451 approaches its conclusion, Montag sees this transformation and begins to relate to fire in a more objective light, specifically, in terms of its use to provide warmth and light and, of particular importance, to enlighten.  As Bradbury wrote in one passage,

“Montag tried to see the men's faces, the old faces he remembered from the firelight, lined and tired. He was looking for a brightness, a resolve, a triumph over tomorrow that hardly seemed to be there. Perhaps he had expected their faces to burn and glitter with the knowledge they carried, to glow as lanterns glow, with the light in them. But all the light had come from the camp fire, and these men had seemed no different from any others who had run a long race, searched a long search, seen good things destroyed, and now, very late, were gathering to wait for the end of the party and the blowing out of the lamps.”

Bradbury’s title, of course, refers to the temperature at which books burn.  Fire used as an instrument of subjugation, however, is a far cry from fire used to illuminate one’s surroundings.

According to Beatty, burning books is a way to eliminate the possibility of strife, conflict, or unpleasant feelings. In his explanation to Montag and Mildred, he says that if any book causes any person or group some unpleasant feelings, then that book should be burned. Beatty reasons that if all books are burned, then there is no possibility that anyone will be offended by a book. Also, as a result, with people reading less, they think less. This might decrease debates and arguments but it comes at the cost of knowledge and variety of opinions. Beatty explains how he thinks burning books establishes peace: 

Coloured people don't like Little Black Sambo. Burn it. White people don't feel good about Uncle Tom's Cabin. Burn it. Someone's written a book on tobacco and cancer of the lungs? The cigarette people are weeping? Bum the book. Serenity, Montag. Peace, Montag. 

That is Beatty's warped position. The general lesson of this novel is that the burning of books symbolizes censorship, the loss of freedom, and the suppression of ideas. Burning books also symbolizes the destruction of creativity. Faber says "Those who don't build must burn." In this novel, the firemen burn books and effectively destroy creative work. Building is associated with creation. It is a contrast of creation versus destruction. 

In terms of imagery, the books resemble birds. "The books leapt and danced like roasted birds, their wings ablaze with red and yellow feathers." Destroying a book is like destroying a bird's ability to fly. If books are burnt, the ideas are snuffed out. Those ideas are less likely to be communicated to many people in many areas. They can not be passed on, shared, and so on. In a very real sense, ideas from books are less likely to travel. Their wings are clipped or "burnt." 

Fire is one of the most powerful symbols in the book. It is seen as a destructive force almost greater than Man; it is used to quell opposition and solve problems by destroying them. For Montag, fire is his entire life; his motto is "It's good to burn." Slowly, though, he stops loving fire as his life and starts to recognize how it is a negative in life, not a positive.

...if he burnt things with the firemen, and the sun burnt Time, that meant that everything burned!

One of them had to stop burning. The sun wouldn't, certainly. So it looked as if it had to be Montag... Somewhere the saving and putting away had to begin again and someone had to do the saving and keeping...(Bradbury, Fahrenheit 451, hrsbstaff.ednet.ns.ca)

Fire there is a symbol for the passage of time; the sun continues regardless of other events, simply because it is so large, but time is valuable to the short-lived people on Earth. Time is burned up by waste and sloth, and Montag has not only burned his own time, but the time of others. Now, he can put his own time to better use; he can create, which allows others down the road to better use their own time; Montag's fire will not be destructive any longer, but instead change from burning time to "cooking" it, making more time for himself and for others through his actions.

In the opening pages of the novel, fire is shown as being a powerful force of destruction.  Montag, wielding the all-powerful fire, is in the throws of intense joy at the scene of a house burning, of books flapping and shriveling in the intense flames.  Fire is a dangerous, awful, fearful thing that when introduced, only represents danger and supression by the government authorities.  It represents your entire life being destroyed if you don't conform.  Ray Bradbury even describes the kerosene that produces the flames as "venomous" and "poison."

As the novel progresses, and nears it end, fire is still a destructive force, but in a more positive way.  It is the force that will destry society, providing Montag and others a fresh start, a chance to rebuild things and make them better, to not make the same mistakes again.  It paves the way for goodness, depth, books, thinking, and human connections to be made in people's lives again.  Fire, throughout the entire novel is used as a force to destroy; the difference is what is done with that force--to tear down the good things about humanity, or to build them up and encourage them.  I hope that helps; good luck!