Eternal Vigilance is the Price of Liberty. "Those who expect to reap the blessings of freedom must, like men, undergo the fatigue of supporting it." The price of liberty and freedom is huge and you will need to go under certain circumstances in order to get what kind of freedom you deserve and need.
Hope This Helps
Do you have any images of the story that you are trying to get the main idea from?
The correct answer they do not want the others to have false hope that someone else is on the island ☺