This is a fight song. Katy sings about people who face some difficulties and are depressed. They make some mistakes, so they want to start again. I can know these things by the phrase of “Do you ever feel like a plastic bag, drifting through the wind, wanting to start again?” The second phrase of “Do you ever feel, feel so paper-thin, like a house of cards, one blow from caving in?” means that Katy wants to ask us if we ever thought that we are not good at anything and weak people. I also think this phrase, “Do you ever feel already buried deep? Six feet under screams, but no one seems to hear a thing” talks about people who are having difficulty in breathing because they feel stress, and they want other people to help them. When it comes to the phrase of “Do you know that there’s still a chance for you? ‘Cause there’s a spark in you”, I think “spark” explains people’s motivation and inspiration, so Katy wants to say that we can still hang on because we have a “spark” in our mind. I also suppose that we can be better as soon as we motivate ourselves, and we can do anything what we want to do freely by the phrase of “You just gotta ignite the light, and let it shine Just own the night like the Fourth of July” Next, the phrase of “’Cause baby, you’re a firework. Come on, show ’em what you’re worth. Make ’em go “oh, oh, oh!” As you shoot across the sky-y-y” explains that Katy wants to tell us the wonderfulness of freedom, so she compares the colorful fireworks to freedom. I think she cheers people who don’t have confidence and she thinks that everyone has great talents and they can have many chances. She tells use not to be afraid of trying to do something! I also think this phrase, “Baby, you’re a firework. Come on, let your colors burst. Make ’em go “oh, oh, oh!” You’re gonna leave ’em falling down oh oh” means individuality is important and we should show more of our own originality. If we do so, we can experience a new world. Katy uses the phrase of “You don’t have to feel like a waste of space. You’re original, cannot be replaced. If you only knew what the future holds. After a hurricane, comes a rainbow” because Katy wants to explain we can’t know our future, but after we overcome the troubles and sadness, happy and pleasant things surely happen. So she wants to tell us not to succumb to our negative feeling and other obstacles. And I can imagine Katy says that infinity possibilities are spread front of us, so we can try to do everything to grasp our best future from the phrase of “Maybe the reason why all the doors are closed. So you could open one that leads you to the perfect road. Like a lightning bolt, your heart will glow. And when it’s time you know” At the end, “Boom” means roar and I think the word expresses the state of releasing our mind. I also think this is a song for people who don’t have the confidence to cheer them and Katy wants to tell them to never give up by the phrase of “Boom, boom, boom. Even brighter than the moon, moon, moon. It’s always been inside of you, you, you. And now it’s time you let it through-ooh-ooh”