What does Cassia realize about Grandfather's risky words that he passed on to her on a paper?

Cassia is with a group of students in from of the Arboretum. They are the first group that is allowed to try the new activity of hiking in many years. They start on a small hill filled with vegetation. Cassia is very excited to be out in nature. It reminds her of her grandfather. She finds a secluded spot and takes out the paper he gave her, trying to memorize the words. It's a risky action, and she can't get caught. The words on the paper captivate her, and she realizes why they were banned by Society. They promote rebellion.