The Hearth and the Salamander' is ripe with meaning. Even the title of the section conjures images relevant to the issues at hand. The hearth conjures images of fire, that tool of destruction used in the novel to censor knowledge and ideas. The salamander is a lizard that myth holds can survive in flames - thereby fostering an image of free thought, personified by Guy Montag, surviving amidst the fires of suppression. The book, that most feared and reviled enemy of the state, is quite significant in this section of the novel, as it is throughout Fahrenheight 451.
Books represent knowledge and awareness.
Like the forbidden fruit in the futuristic Eden that is Montag's society, books are forbidden by the state in its hubris. Books are referred to metaphorically and in simile as birds, their pages wings. Transversely, it seems, they represent freedom that knowledge brings and that freedom's ability to transcend - to fly. The significance of fire is also manifold. Fire represents purification as it is used to rid society of that which is undesirable.