A young, delicate man of a sensitive nature, the Reverend Arthur Dimmesdale is very well educated, with what seems to be a deep philosophical turn of mind. When he is first introduced in Hawthorne's novel in Chapter II, as Dimmesdale appears with the stringent Puritan, the Reverend Wilson, his philosophical mind seems to be superior as he defends Hester's refusal to name her paramour, contending that
were wronging the very nature of woman to force her to lay open her heart's secrets in such broad daylight, and in presence of so great a multitude.
Of course, already he is being hypocritical as he desires to keep Hester quiet with their secret. And, although he again defends Hester in Chapter VIII after Hester has been summoned to the Governor's Hall, he is guilty of selfish motives as, speaking in the greatest of ironies, Hester turns to him for succor, pleading,
“Thou wast my pastor, and hadst charge of my soul, and knowest me better than these men can. I will not lose the child! Speak for me! Thou knowest,—for thou hast sympathies which these men lack!—thou knowest what is in my heart, and what are a mother's rights, and how much the stronger they are, when that mother has but her child and the scarlet letter!..."
Still, he does defend Hester, holding his hand over his trembling heart,with his large dark eyes that hold "a world of pain in their toubled and melancholy depth."
Thus, Dimmesdale earns much respect in his defence of Hester as he seems willing to risk censure for his charity and philosophy. However, after Roger Chillingworth chooses the minister for his spiritual guide, the Reverend Dimmesdale grows emaciated and his voice carries with it a "certain melancholy prophecy of decay in it." Indeed, it is at this point in Chapter IX that Dimmesdale's health reflects the decay of his soul as he has become a sanctimonious hypocrite who rationalizes his concealment of his sin. Added to this, Chillingworth attempts to burrow into the soul of the minister in order to uncover the secrets of his heart.
So burdened is Dimmesdale with his secret sin and hypocrisy that he yearns to confess from his pulpit, but he cannot overcome his fear of condemnation by the community. Moreover, even when he does confess his inferiority, the congregation mistakes his speech for humility: "The godly youth!" they exclaim. Rather than encourage him, their sentiments drive him to scourging himself as was done in "the old, corrupted faith" Although this provides Dimmesdale no relief from his terrible guilt. In another effort to purge himself of the darkness of his soul, he stands one night on the scaffold. But, as he imagines people seeing him in this ignominious posture, Dimmesdale bursts into hysterical laughter at his weakness. His secretiveness and emotional suppression certainly begin at this point to incite his physical demise. As Hawthorne writes,
No man, for any considerable period, can wear one face to himself, and another to the multitude, without finally getting bewildered as to which may be the true.
The subversion of his conscience and the facade that he must wear destroys Arthur Dimmesdale. With Chillingworth as his "bitterest of enemy" Dimmesdale is further tortured. Finally, out of desperation, he confesses on the scaffold, but this time he invites Hester and Pearl, who kisses him, breaking "a spell." After seven years of torment, Dimmesdale frees himself from the hypocrisy and Puritan fear that have destroyed him.
Dimmesdale is held in high public esteem as a minister; in the extremely religious community in which he lives, no office could be more highly regarded. However he has also committed adultery, which is one of the gravest of sins in the eyes of this community. That is why he keeps it secret for as long as he possibly can. But at the end his sin is finally revealed in public. In this way he falls from public grace - although he also forestalls any punishment from the community as he dies at this climactic moment. In any case, any condemnation he might have faced from the community would have been no worse than his own sense of guilt which afflicts him for many years, and which Hester's wronged husband Roger Chillingworth works upon to torment him even further. This internal guilt causes him to literally waste away.