“I have a strange fancy,” observed the sensitive minister, “that this brook is the boundary between two worlds, and that thou canst never meet thy Pearl again. Or is she an elfish spirit, who, as the legends of our childhood taught us, is forbidden to cross a running stream? Pray hasten her; for this delay has already imparted a tremor to my nerves.”
Hester watches as Pearl walks up to the stream and stops on the other side, still standing in a ray of sunlight. Dimmesdale is anxious that Pearl should cross the stream, and he asks Hester to make her hurry.Dimmesdale fears that if Hester should alter her appearance and manner while Pearl plays beyond the stream, Pearl might become estranged. Pearl cannot imagine her mother without the letter; it may be a centering emblem of security. Pearl also seems to see herself as the living embodiment of the letter, and to throw it away would be to throw her away—remember that to Pearl it is not a badge of shame so much as a badge of love.
http://www.gradesaver.com/the-scarlet-letter/study-guide/section6/
