The purpose of the second to last paragraph of chapter 5, "Hester at Her Needle," is to explain one of the fundamental lessons that wearing the scarlet letter has taught Hester. Identify this lesson and explain how Hawthorne's use of diction, syntax, figurative language, irony, and tone achieves his purpose.

As Hester Prynne walks "to and fro" in the community, she notices how certain people that she passes gaze at her scarlet A, "the ignominious brand" on her bosom. When these people look at the letter, there is often more than a quick glance. In their momentary pause, Hester notices that there is a reaction to this letter. Sometimes she believes that she observes "a momentary relief," and it is as though the other person shares her "agony." Perhaps they, too, are adulterers who are guilty of the same sin, though they wear no mark.
Also, Hester finds that her wearing of the scarlet letter somehow gives her

a sympathetic knowledge of the hidden sin in other hearts. (Ch. 5)

Since she dwells in a Puritan community where sin is strongly condemned, Hester does not want to think that in many a heart there is a secret sin. In fact, Hester now feels confused and disillusioned. In her mind she addresses the Devil:

O Fiend, whose talisman was that fatal symbol, wouldst thou leave nothing, whether in youth or age, for this poor sinner to revere? (Ch. 5)

Because her heart gives "a sympathetic throb" as she passes certain ministers or magistrates, and she feels "a mystic sisterhood" when she observes other women looking at her, Hester is especially concerned that many others may carry in their hearts a secret sin that resembles her transgression. This thought of the possibility of hidden sins in the hearts of others causes Hester to become disillusioned.

Such loss of faith is ever one of the saddest results of sin. . . . Hester Prynne yet struggled to believe that no fellow-mortal was guilty like herself. (Ch. 5)

As Hester walks, her observations are shaded by a pessimistic tone, for Hester feels discouraged that others may be no better than herself. Certainly, Hawthorne's diction, his use of such words as "loss," "saddest," "fatal," and "hidden sin," suggests a new gloom that pervades Hester's spirit. For she has lost her faith in mankind as she realizes that in many a heart there lies a secret sin. Also, there is a bitter irony to her thoughts, as she is the only one wearing the ignominious symbol that figuratively "burns into her heart" with her shame and the scorn of others, who in fact may be sinners themselves.