This is of course an incredibly rich and complex text with many meanings that have been attached to it. It is impossible therefore to come up with one overall meaning to this text, as there are several that vie for supremacy. However, this text can be read as a philosophical study concerning sin and knowledge. What is slightly ironic about this novel is that the punishment that Hester Prynne receives for her crime of adultery is actually something that, far from reintegrating her into society, thrusts her away from society and keeps her on the very edge of respectable living, as the following quote describes:
But Hester Prynne, with a mind of native courage and activity, and for so long a period not merely estranged, but outlawed, from society, had habituated herself to such latitude of speculation as was altogether foreign to the clergyman. She had wandered, without rule or guidance, in a moral wilderness... 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.
Having the scarlet letter emblazoned on her bosom has forced her to wander in a "moral wilderness" and to form her own independent intellectual approach to life around her. The author thus examines the role of sin and punishment in his world and is indirectly critical of the way in which methods of punishment that were meant to reintegrate offenders back into the society whose norms they had just flouted so often leave those punished "without rule or guidance" on the edges of society, where their characters are formed and developed in ways that are surprisingly subversive.
In "The Scarlet Letter", the scarlet letter is basically a symbol of Hester's adultery. She was publicly punished and forced to wear the letter on her bosom as a symbol that she has committed a terrible sin. The symbol is intended to be ugly; but with Hester's skillful embroidery, she transform it into a beautiful symbol. Through all the humiliation, Hester keeps her head held high. Her symbol is an outward symbol that reveals her sin while others hide their sin. As the story progresses, Hester spends hours helping the sick and needy. She gains respect from some of the town's people. Many people changed the interpretation of the letter to "Able".