What "general symbol" has Hester become?

Whereas at first it represented Hester's adultery and her needlework skills, it now takes on two more meanings. First, the letter begins to represent the hidden shame of the community. Preachers stop in the street and address their fiery words towards Hester, and she becomes a lightning rod for all sin, for all the latent build-up of repressed rage fomented by the strict morals and codes of the society. The more the community unloads its hatred and judgment upon Hester, the more it can use her as an example or deterrent in the name of eradicating sin.

Hester also can sense when people sympathize with her, perhaps because of their own secret sins. Thus the letter serves as a gateway into other people's secret crimes, and it acts as a focal point for the shame of the entire community. The letter thus can be interpreted as a symbol of shame shared by everyone rather than by Hester alone.