In the novel, Lord of the Flies by Wiiliam Golding, Ralph stands up to Jack and the entire tribe after they steal Piggy's glasses. This shows that Ralph is brave.
To take control over Ralph's group, Jack's way was by stealing the glasses. This is an allusion to the myth of greek's of Prometheus who stole fire from the god, Similarly, Jack stole the glasses of Piggy and taking away the power from them. Therefore, Ralph could not resist having the glasses or power with Jack and along with his tribe, he decides to chase them to retrieve the glasses.