The isolation experienced by the main characters of Nathaniel Hawthorne's The Scarlet Letter brings about significant changes in their positions in the community. Isolation also causes their self-perceptions to become altered.
While it is known that science has found that the brains of lonely people react differently from those with active social networks, Nathaniel Hawthorne demonstrates an early perspicacity (a keen insight) in this matter in his Introductory to The Scarlet Letter, "The Custom House." From his observations of the isolated role of the Custom-House officer, who does not "share in the united effort of mankind," Hawthorne draws the conclusion that such a single soul loses his own "proper strength" and becomes weakened in his "original nature" and its self-reliance and courage. Further, Hawthorne exemplifies these observations in the characters of the narrative that follows his introduction.
Hester Prynne's scarlet letter and "the innumerable throbs of anguish that had been so cunningly contrived for her" set her strangely apart from the Puritan community. People stare at her prominent scarlet letter or children pursue her with shrill cries,
Every gesture, every word, and even the silence of those with whom she came in contact, implied, and often expressed, that she was banished, and as much alone as if she inhabited another sphere. (Ch.5)
There are times when she feels that a person looks at her scarlet letter; this look gives her a feeling of "momentary relief--as if half of her agony were shared." Then, too, there are other times that she can not help feeling that "the red infamy upon her breast" lends her "a sympathetic knowledge of the hidden sin in other hearts." At other times,
...a mystic sisterhood would contumaciously assert itself, as she met the sanctified frown of some matron, who, according to the rumor of all tongues, had kept cold snow within her bosom throughout her life....Or once more, the electric thrill would give her warning,--"Behold Hester, here is a companion!"--and, looking up, she would detect the eyes of a young maiden glancing at the scarlet letter shyly and aside, and quickly averted, with a faint, chill crimson in her cheeks....(Ch.5)
These moments of "mystic sisterhood" are sadly short-lived, however, and Hester returns to her life apart from the community. Since she is isolated from the Puritan society, the solitary Hester decides to allow herself more freedom of thought.
. . The scarlet letter was her passport into regions where other women dared not tread. Shame, Despair, Solitude! These had been her teachers,—stern and wild ones,—and they had made her strong, but taught her much amiss. (Ch.18)
Because of her profound alienation, Hester finds herself forced into the role of her own philosopher as she is placed into "a moral wilderness." Later, with no rules or guidance to limit her, Hester later feels confident in hers and the minister's decision to run away to Europe, whereas the Reverend Dimmesdale is uncertain.
After she leaves the Puritan community for England and returns years later, Hester again wears upon her bosom the scarlet letter: "And Hester Prynne had returned, and taken up her long-forsaken shame!" (Ch.24) However, Hester's situation differs because the letter becomes not so much a symbol of ostracism from society as that of sympathy and sorrow set apart for her.
But...the scarlet letter ceased to be a stigma which attracted the world’s scorn and bitterness, and became a type of something to be sorrowed over, and looked upon with awe, and yet with reverence, too. (Ch.24)
The Reverend Dimmesdale feels isolated because of his guilt over his sin of adultery committed with Hester. Because his is a secret sin, Dimmesdale internalizes his guilt and feels isolated from the community in his acts of hypocrisy as their minister. The minister imposes self-flagellation to rid himself of his guilt, but this physical punishment does not allay his feelings of sinfulness. When he tries to proclaim his guilt publicly with the words of his sermons, the members of the congregation believe that he is speaking allegorically, and they find him humble in his acclamations of being a sinner. Finally, his sinful isolation and inability to reveal himself eat away at Dimmesdale to the point that he "loses his own proper strength" as Hawthorne has earlier noted. Weakened by this loss of his "own original nature," the minister dies after he publicly confesses his secret sin and exposes his own scarlet letter upon his chest.
Roger Chillingworth learns of his wife's crime of adultery and watches her as she stands on the scaffold. It is then that he plans his revenge. Operating under the guise of a doctor, or "leech," Chillingworth attaches himself to his victim, the Reverend Dimmesdale. Isolated from everyone else in the community as a stranger, Chillingworth stays with Dimmesdale and focuses on getting the minister, whom he suspects of committing adultery with his wife Hester, to reveal himself.
Because of his isolation from the community and all that is worthy and good, along with his insidious actions and cruel intentions to expose the minister's sins, Chillingworth transforms into a fiend. He becomes
...a chief actor in the poor minister's interior world. He could play upon him as he chose.
One night as the Reverend Dimmesdale sleeps, Chillingworth thrusts open the shirt which the minister wears, exposing the manifestation of guilt: A raised letter A is on the Reverend Dimmesdale's chest.
Later, Chillingworth's plan to expose Dimmesdale fails because the minister asks Pearl to join him and Hester as they stand on the scaffold, the one place where the evil Chillingworth cannot reach them. When the old leech sees the three standing together on the platform, he hurries to them. "Thou hast escaped me!" this fiend tells Dimmesdale. "May God forgive thee!" the minister replies.
As the incarnation of the sin between the minister and Hester, and as the "messenger of anguish," Pearl is isolated from the other children of the Puritan community. Since Pearl is "an imp of evil, emblem and product of sin" (Ch. 6), she is taunted by the other children and not allowed to play with them. When they approach her, Pearl throws stones at the children while screaming something like "a witch's anathemas in some unknown tongue." (Ch.6)
Pearl is described as an "elf-child" who "lacked reference and adaptation to the world into which she was born. The child could not be made amenable to rules." She is a free spirit, the incarnation of the love of Hester and Arthur Dimmesdale. Alienated from the Puritan world that demands order, little Pearl is a free spirit who delights in the sounds and sights of Nature.