"You'll live and get hurt," she said, in the dark. "But when it's time, tell me. Say goodbye. Otherwise, I might not let you go. Wouldn't that be terrible, to just grab ahold?"
Jim's mother tells Jim that he cannot live life without being hurt. He tells her that he never plans on being hurt, but she knows that this is not a possible way of life. Jim's mother realizes that her son is trying to live life a way that it cannot be lived. He is the ultimate child, living each moment individually, never stepping back from life to ponder it or wonder. Jim goes from adventure to adventure and insists on remaining free and independent, but his mother knows that only children can be that way. What Jim truly fears, to be grounded, to lose some of his precious freedom, is what she threatens him with if he does not at least say goodbye to her before he leaves for good. But her threat is not really a terrible thing. Jim's mother wants him to let go a little bit of his independence so that he will let other people into his life, even though those people could hurt him. Her life will be better if she can hold onto her son sometimes and she knows that he will need someone to hold onto eventually. Much of the book can be viewed as Jim's struggle against curbing his freedom and allowing others into his life.