Dualities are the most elementary of comparisons, and are the easiest for the mind to comprehend in that total opposites are brought to attention. These opposites subconsciously provide one with a deeper insight of the material and consciously entertain. In Ray Bradbury's Fahrenheit 451, many dualisms are included both within Montag and in the outside world that provide 180 degree flip-side views, giving the book further depth and inner meaning.

Within the many layers of Montag lay several opposite sides. For example, Montag is a fireman who burns books for a living but at home, spends time reading novels, poetry, and other written material. Although Montag could be called a hypocrite, he does not enjoy both the reading and the burning at the same time; he goes through a change that causes him to love books. Humans have the power to change and grow from one extreme to another, sometimes for the better and sometimes for the worse. In addition, when Mildred is with Montag, Montag does not have feelings for her but thinks of her as she is killed by the bombs. He possesses both the knowledge that Mildred does not love him and the heart that truly cares, but he knows not how to deal with this. His feelings are oppressed; it takes a major event (the bomb) to jolt them from hibernation.

There are many dualisms in the outside world of Fahrenheit 451. For example, Montag receives contrasting lectures from Faber and Beatty on what to do with the books and how to be. Beatty and Faber are like black and white: total opposites no matter how you look at it. This "flip-side of a coin" clearly compares the book burner to the book reader, the hatred to the love, and it also gives the reader the opportunity to "choose" their side. In addition, the fire is used to burn houses and books, to destroy possessions; it also is used by the outcast men to cook their meal, warm themselves, and provide light for them. The fire has, in itself, two conflicting sides which includes destruction and preservation. The fire gives Montag as well as the reader the understanding that one thing can have both good qualities and bad qualities at the same time, and that many powers can be spoiled if used for negative intentions.

These contrasts all give two perspectives on an issue, whether that be directly or indirectly. The dualisms are the foundation of much of the symbolism found within the book. It gives the book substance, meaning, and character that will keep Fahrenheit 451 on all bookshelves worldwide for eternity, or at least until Beatty and the "firemen" get to it.