Nathaniel Hawthorne creates a dichotomy in The Scarlet Letter by aligning characters with either darkness or light. Those who are part of the dark are part of the world of sin and repression, while characters who are part of the light portray innocence and freedom.
The character that embodies darkness most thoroughly is Roger Chillingworth. He appears on the scene after spending years in the "wilderness." He dresses in dark clothes and emerges from the forest, which Hawthorne equates with sin and the devil. When he asks Hester to join in his deception by keeping the secret of his identity, she overtly asks him if he is evil.
"Why dost thou smile so at me?" inquired Hester, troubled at the expression of his eyes. "Art thou like the Black Man that haunts the forest round about us? Hast thou enticed me into a bond that will prove the ruin of my soul?"
Dimmesdale is also part of the darkness, although he is not as dark as Chillingworth. While Chillingworth is being deceptive to exact revenge, Dimmesdale is a coward. He is afraid to admit to being Pearl’s father, but his guilt torments him—so much so that he is driven to stand on the scaffold, in the place of shame Hester occupied. But he cannot do it in mid-day like she did.
It was an obscure night of early May ... There was no peril of discovery. The minister might stand there ... Without any effort of his will, or power to restrain himself, he shrieked aloud.
Dimmesdale is torn between wanting to confess and fearing discovery, but at this point, fear wins, and he maintains his pretense. He stays hidden in the dark of night.
The exact opposite is Pearl, the little girl who is always described as being part of the light. During Hester’s visit to the mansion, Pearl is drawn to the sunlight shining through the windows.
Pearl, looking at this bright wonder of a house began to caper and dance, and imperatively required that the whole breadth of sunshine should be stripped off its front, and given her to play with. "No, my little Pearl!" said her mother; "thou must gather thine own sunshine. I have none to give thee!"
The light makes Pearl even more lively, dancing around energetically. When she asks Hester to give the light to her to play with, Hester tells her that she has none herself. This contrast between mother and daughter is most vividly seen in their excursion into the forest. Pearl runs ahead and plays in the light, her natural environment. But Hester cannot be part of the light. Her guilt and sin keep her in the dark.
The light lingered about the lonely child, as if glad of such a playmate, until her mother had drawn almost nigh enough to step into the magic circle too. "It will go now!' said Pearl shaking her head. "See!" answered Hester, smiling. "Now I can stretch out my hand and grasp some of it." As she attempted to do so, the sunshine vanished.
During her meeting with Dimmesdale in the forest, she decides to discard the symbol of her sin, the scarlet "A." The darkness instantly departs from her, and she is radiantly beautiful again. She sheds the mark of shame and the guilt that Puritan repression has placed on her. But Pearl does not recognize her mother without the "A," which represents the darkness of her shame, so Hester puts it back. The radiance disappears immediately.
As if there were a withering spell in the sad letter, her beauty, the warmth and richness of her womanhood, departed, like fading sunshine; and a gray shadow seemed to fall across her.
Hester cannot truly discard her guilt until the truth comes out into the light. When Dimmesdale confesses that he is the father and mounts the scaffold in front of the congregation, the light overcomes the darkness.
The sun, but little past its meridian, shone down upon the clergyman, and gave a distinctness to his figure, as he stood out from all the earth to put in his plea of the guilty at the bar of Eternal Justice.
Dimmesdale chooses to come out of his self-imposed darkness, which allows the light to shine on Hester, himself, and Pearl.