With the character of Arthur Dimmesdale, Hawthorne introduces the concept of psychosomatic symptoms as the Reverend holds his heart and, as is later revealed, has a letter "A" raised upon his chest. Dimmesdale's health is deteriorating because of his desperate guilt. When he attempts to confess by calling himself a worse sinner than anyone else in his sermons, the congregation interprets his words as saintly humility and regard him even more highly than previously.
In his desperation, Dimmesdale turns to self-flagellation to punish himself. But, this action does nothing to soothe his soul. So, in Chapter 12 he walks "in a shadow of a dream" to the "spot of public ignominy," the scaffold where Hester once stood. There is overcome with
a great horror of the mind as if the universe were gazing at a scarlet token on his naked breast, right over his heart.
Dimmesdale's shame evolves from his feelings of guilt because of his tremendous hypocrisy. He, more than any other character, personifies the evil of Puritanism's refusal to forgive the sinner, causing a greater evil, that of the worm of hypocrisy which eats away at the soul.
Chillingworth continues to play mind games with Dimmesdale, making his revenge as terrible as possible. The minister often regards his doctor with distrust and even loathing, but because he can assign no rational basis to his feelings, he dismisses them and continues to suffer. Dimmesdale’s suffering, however, does inspire him to deliver some of his most powerful sermons, which focus on the topic of sin. His struggles allow him to empathize with human weakness, and he thus addresses “the whole human brotherhood in the heart’s native language.” Although the reverend deeply yearns to confess the truth of his sin to his parishioners, he cannot bring himself to do so. As a result, his self-probing keeps him up at night, and he even sees visions.