Not unreasonably, Montag expects that reading will bring him intellectual nourishment and fulfillment. But he's to be greatly disappointed. Even after rereading the pages several times, the words beneath his eyes still don't make any sense. Montag lives in a society in which people are actively discouraged from having intelligent thoughts or engaging in deep thinking. Instead, they're expected to lead lives of mindless consumerism and instant gratification. To the totalitarian regime in this dystopian nightmare, any kind of independent thinking is dangerous, hence the necessity of burning books.
At this point in the story, Montag starts to develop into a rebel against the regime he'd previously served with such loyalty and enthusiasm. And what greater act of rebellion can there be in this society than reading a book? But Montag's capacity for intellectual growth is as stunted as everyone else's in this society. He knows that books are important and that they are vital to his personal awakening as an opponent of the regime. But at this stage, he realizes that there's still a long way to go before he can really feel in the depths of his being any kind of fulfillment through reading books.