Because as we say the stuff that we need to say in an attitude it actually shows us being happy, mad or whatever but when we are writing you could just be sarcastic like “ yea it was a great day!” When it really wasn’t
The significance of this quote is Montag's realization of what his job is actually about and what it implies. He became a fireman because he was meant to. However, he is now haunted by this new feeling and does not know anymore what is right and what is wrong.