Parallel to the telling act of Hester's donning the scarlet letter and not freeing herself from her shame despite the reiterpretation of the symbolic "A" in Chapter XIII, is the despair of the Reverend Dimmesdale which is also revealed. When Chillingworth tells Hester in Chapter XIV that there are rumors that the magistrates may allow her to remove her scarlet letter, she responds,
Were I worthy to be quit of it, it would fall away of its own nature, or be transformed into something that should speak a different purport.
Likewise, the Reverend Dimmesdale feels that he is not worthy of surcease from his suffering. When Hester asks him if he has found peace, he answers, "None!--nothing but despair!" He tells Hester that his scarlet letter "burns in secret!" Then, Hester urges him to leave Boston and start a new life elsewhere, but he resists, so Hester makes it strongly, urging him to change his name and start a new life. But, the minister lacks the strength to make such a change because of his deep sense of guilt.
In Hester's resuming the wearing of the scarlet letter and in Dimmesdale's despairing acceptance of his fateful guilt, tragically, both Puritans deny the freedom of the will. These acts are pivotal to Hawthorne's criticism of the stultifying effects of Puritanism, the moral cowardice and hypocrisy that it engenders.
Although there are several significant moments in these chapters, which include Hester's meetings with both Dimmesdale and Chillingsworth, and her realization that she essentially hates her husband, I would argue that the most important moment is when Hester throws the scarlet letter from her.
At this moment, Hester is determined to take charge of her own fate, and she symbolically rejects the judgment of the town, while reclaiming her own innocence. This is important for her development as a character, especially in contrast to Dimmesdale, whose weakness is basically killing him. Removing the letter reveals Hester as she should be, hair and soul free from arbitrary punishment. Yet even in this moment she cannot be truly free. The idealism of the three together as a family will never be realized, & this is foreshadowed by two things. First, Hester throws the letter, but instead of landing in the water where it would be swept away, it lands in the bushes. There it sits, a reminder of the reality in which she lives. Similarly, Pearl is reluctant to approach her mother and Dimmesdale, suggesting that the scene is somehow not right.