In the opening scene, Bradbury describes Montag burning books. Bradbury's intention is to show the enjoyment and spectacle of burning. Montag takes a deep delight in it. It is has the aspect of a party for him. We learn that he would like:

to shove a marshmallow on a stick in the furnace, while the flapping pigeon-winged books died on the porch and lawn of the house.

This opening scene is our one and only glimpse of the "old" Montag, the Montag who is at one with his job and his society. He isn't, at this point, thinking about the implications of what he is doing or of whether it is right or wrong to burn books. He has buried his own dissatisfactions and is able to let out his aggressions in a socially acceptable way through the destructive nature of his job. The opening imagery makes his book burning seem enjoyable, even beautiful.

All of this will quickly change, for Montag will meet Clarisse, and she will challenge him to live more deeply. Further, he will soon have to face Mildred's attempted suicide. His carefully constructed life is soon to fall apart as he struggles to find his better self.

Well said, Cadena!  You've hit upon nearly everything I discuss with my students when beginning the novel.  The only thing I can think to add to this discussion is that fact that while most firemen appear to be nearly emotionless, or at least not overly passionate about anything, Montag takes a unique and perhaps unusual pleasure in doing his work.  I believe this sets him apart from many of the other firemen, except for his captain.  Also, it shows that his ability to experience true passion will be his downfall in terms of his fireman career; when he becomes disillusioned with what he is doing, he needs to find something else to consume him.  In this case, he decides to search for the meaning held within books, and plunges into a secret society of individuals who dedicate themselves to the preservation of books and their all-too-important messages.