For those of you who read this back in the dark ages of high school, you will remember it takes place in Puritan Boston and Hester is a known adulterer given her lack of a husband and her infant daughter just born. She is branded with the scarlet letter but refuses to reveal her paramour.
Rev. Dimmesdale is a staunch reformer but in chapter 11 you see what his interior life is like and his torment between his perception of his own sin shame and the way his community views him (as near saint).
It is inconceivable, the agony with which this public veneration tortured him. It was his genuine impulse to adore the truth, and to reckon all things shadow-like, and utterly devoid of weight or value, that had not its divine essence as the life within their life. Then what was he?—a substance?—or the dimmest of all shadows? He longed to speak out from his own pulpit at the full height of his voice, and tell the people what he was. “I, whom you behold in these black garments of the priesthood—I, who ascend the sacred desk, and turn my pale face heavenward, taking upon myself to hold communion in your behalf with the Most High Omniscience—I, in whose daily life you discern the sanctity of Enoch—I, whose footsteps, as you suppose, leave a gleam along my earthly track, whereby the Pilgrims that shall come after me may be guided to the regions of the blest—I, who have laid the hand of baptism upon your children—I, who have breathed the parting prayer over your dying friends, to whom the Amen sounded faintly from a world which they had quitted—I, your pastor, whom you so reverence and trust, am utterly a pollution and a lie!”
More than once, Mr. Dimmesdale had gone into the pulpit, with a purpose never to come down its steps until he should have spoken words like the above. More than once he had cleared his throat, and drawn in the long, deep, and tremulous breath, which, when sent forth again, would come burdened with the black secret of his soul. More than once—nay, more than a hundred times—he had actually spoken! Spoken! But how? He had told his hearers that he was altogether vile, a viler companion of the vilest, the worst of sinners, an abomination, a thing of unimaginable iniquity, and that the only wonder was that they did not see his wretched body shrivelled up before their eyes by the burning wrath of the Almighty! Could there be plainer speech than this? Would not the people start up in their seats, by a simultaneous impulse, and tear him down out of the pulpit which he defiled? Not so, indeed! They heard it all, and did but reverence him the more. They little guessed what deadly purport lurked in those self-condemning words. “The godly youth!” said they among themselves. “The saint on earth! Alas! if he discern such sinfulness in his own white soul, what horrid spectacle would he behold in thine or mine!” The minister well knew—subtle, but remorseful hypocrite that he was!—the light in which his vague confession would be viewed. He had striven to put a cheat upon himself by making the avowal of a guilty conscience, but had gained only one other sin, and a self-acknowledged shame, without the momentary relief of being self-deceived. He had spoken the very truth, and transformed it into the veriest falsehood. And yet, by the constitution of his nature, he loved the truth, and loathed the lie, as few men ever did. Therefore, above all things else, he loathed his miserable self!
His inward trouble drove him to practices more in accordance with the old, corrupted faith of Rome than with the better light of the church in which he had been born and bred. In Mr. Dimmesdale’s secret closet, under lock and key, there was a bloody scourge. Oftentimes, this Protestant and Puritan divine had plied it on his own shoulders, laughing bitterly at himself the while, and smiting so much the more pitilessly because of that bitter laugh. It was his custom, too, as it has been that of many other pious Puritans, to fast—not however, like them, in order to purify the body, and render it the fitter medium of celestial illumination—but rigorously, and until his knees trembled beneath him, as an act of penance. He kept vigils, likewise, night after night, sometimes in utter darkness, sometimes with a glimmering lamp, and sometimes, viewing his own face in a looking-glass, by the most powerful light which he could throw upon it. He thus typified the constant introspection wherewith he tortured, but could not purify himself. In these lengthened vigils, his brain often reeled, and visions seemed to flit before him; perhaps seen doubtfully, and by a faint light of their own, in the remote dimness of the chamber, or more vividly and close beside him, within the looking-glass. Now it was a herd of diabolic shapes, that grinned and mocked at the pale minister, and beckoned him away with them; now a group of shining angels, who flew upward heavily, as sorrow-laden, but grew more ethereal as they rose. Now came the dead friends of his youth, and his white-bearded father, with a saint-like frown, and his mother turning her face away as she passed by. Ghost of a mother—thinnest fantasy of a mother—methinks she might yet have thrown a pitying glance towards her son! And now, through the chamber which these spectral thoughts had made so ghastly, glided Hester Prynne leading along little Pearl, in her scarlet garb, and pointing her forefinger, first at the scarlet letter on her bosom, and then at the clergyman’s own breast.
None of these visions ever quite deluded him. At any moment, by an effort of his will, he could discern substances through their misty lack of substance, and convince himself that they were not solid in their nature, like yonder table of carved oak, or that big, square, leather-bound and brazen-clasped volume of divinity. But, for all that, they were, in one sense, the truest and most substantial things which the poor minister now dealt with. It is the unspeakable misery of a life so false as his, that it steals the pith and substance out of whatever realities there are around us, and which were meant by Heaven to be the spirit’s joy and nutriment. To the untrue man, the whole universe is false—it is impalpable—it shrinks to nothing within his grasp. And he himself in so far as he shows himself in a false light, becomes a shadow, or, indeed, ceases to exist. The only truth that continued to give Mr. Dimmesdale a real existence on this earth was the anguish in his inmost soul, and the undissembled expression of it in his aspect. Had he once found power to smile, and wear a face of gaiety, there would have been no such man!
This is a long quote but you can see the psychological and spiritual torture of unconfessed sin and the public/private divide. At one level Dimmesdale is painted as one who can really relate too the common sinner. At another level, he is tortured by his living a false persona.
Knuckleball (Blue Rider Press, 2012).
Am reading a very helpful book by 
Musings on Faith and Psychology 