This is the biggest piece of symbolism even the whole book was titled after it. The letter means much to Hester Prynne. She is made to wear it as a symbol of shame, originally. But the bright red letter that was sewn into her identity was not going to get to her. She wore it knowing that it doesn't fully define her and she won't let other people in her society define her as just an adultress. She begins to work hard and the public begin to view her differently, and the "A" begins to mean something different to them. Able. When she was allowed to take the letter off, she even continued to live with it.

Not only is she a character, but she is also a symbol. "...and little Pearl, herself a symbol..." She is a living reminder to both the minister and Prynne of the sin they committed. But, she is not just a burden on both of them; she is both a blessing and a curse. They both love her very much, and she ties them together, "...as if the mother and the child were communicating their vital warmth to his half-torpid system. The three formed an electric chain." Hester Prynne does whatever she can for Pearl, she is Prynne's driving factor when she is in need, and the physical embodiment of hope and redemption.

Hester Prynne and Arthur Dimmesdale deal with their sins in very contrasting ways. Prynne feels no fear in showcasing what she's been through to the public. To the point where she proceeds to wear the letter even after she is told she doesn't have to.
Whilst Dimmesdale keeps his guilt inside him, and Prynne helps him with keeping it a secret by not telling anybody who the man was for seven years. Her keeping the fact she sinned open is freeing, and she does this to show the public she won't subject herself to the "shame". Meanwhile, Dimmesdale's guilt is constantly hurting him and is a constant burden on his shoulders, which becomes sounbearable to the point where he is screaming to the world the night of the comet. This is not the only time the guilt he keeps inside him finally makes him explode, it is also when he finally reveals to the public that he is the man that committed adultery with Prynne.

A big theme in The Scarlet Letter is sin. The book tells a story about a woman, Hester Prynne, who has committed adultery, with a man named Arthur Dimmesdale. Adultery is a sin in the Christian religion, the religion in which Puritans followed (Puritans were Protestant, which is the second largest form of Christianity). Hester Prynne, is forced to wear the Scarlet Letter "A". Dimmesdale is also forced to live with the guilt, that he, a minister, has committed a sin and could not confess it. The sin and guilt puts him into a spiral of pain until, just before his death, he finally confesses. The book's overarching plot is about adultery, so there is no surprise that one of the biggest themes is focused on sin.