By Bradbury's own admission, the thematic obsession that explicitly emerges in Fahrenheit 451
is the burning of books, the destruction of mind-as-printed-upon-matter. And although Bradbury never uses the word "censorship" in the novel, you should be aware that he is deeply concerned with censorship. Book burning is a hyperbolic phrase that describes the suppression of writing, but the real issue of the novel is censorship.
In looking at censorship in Fahrenheit 451, Bradbury sends a very direct message showing readers what can happen if they allow the government to take total control of what they do (or do not) read, watch, and discuss. For example, the government in Fahrenheit 451 has taken control and demanded that books be given the harshest measure of censorship -- systematic destruction by burning.
Although the books and people have fallen victims to censorship in Fahrenheit 451, luckily, some citizens remain who are willing to sacrifice their lives to ensure that books remain alive. As Faber notes in a conversation with Montag, "It's not books you need, it's some of the things that once were in books." Faber then continues this conversation with Montag pointing out that people need "the right to carry out actions based on what we learn (from books). . . ."