As the sun set on the crumbling city, Emma and her friends huddled in an abandoned library, surrounded by the remnants of a world that once was. The shelves, now covered in dust and cobwebs reminded her of the lost knowledge and civilization destroyed by the zombie invasion. Each creak and groan of the old building reminded them of the lurking danger outside. The relentless zombies, their twisted forms shuffling in the streets, were the ever-present enemy, they lived in a constant battle between life and death. Despite the dire circumstances, Emma clung to a small, tattered book of poetry she had found, to her the words filled her with hope and reminded her of the beauty left in the world.
What is the main theme of the paragraph?