"Because it is a declaration of my intent," Hermione smiled. "I vow to leave this tome here. It is full of all the great moments in Harry’s life, especially the ones he’s shared with me. When he reads them his heart will be so full of joy that it will shield him from these darknesses all around, and show him the way home. Then, when we write the final chapter together, we will read it out loud ... and banish these evils from his mind for good."