Nathaniel Hawthorne's quote is as follows:
“Be true! Be true! Be true! Show freely to the world, if not your worst, yet some trait whereby the worst may be inferred!”
At the root of this challenge is telling the truth: being honest. The quote urges the listener to be honest with the world—if not in sharing one's worst trait, then by at least hinting that there is an imperfection. This seems to refer to exposing one's sinful nature, if not the specific sin itself. And this is especially appropriate for the Reverend Arthur Dimmesdale.
In Nathaniel Hawthorne's The Scarlet Letter, one man has engaged in an adulterous relationship with Hester Prynne years before: but Dimmesdale has never accepted responsibility for his part in their affair. Hester has given birth to their child and been punished and humiliated before the entire community, but she has refused to expose the man who has fathered her child, who is also guilty of the sin.
Dimmesdale is a man torn between wanting to live a righteous life while leading the members of this Puritan community toward sinless lives, and dealing with the hypocrisy of his own behavior and his own sinful nature. In Chapter Twelve, Pearl calls to Dimmesdale as the quote does: asking if he will reveal his connection to Pearl and Hester—on the scaffold the following day, for all to see:
"Minister!" whispered little Pearl.
"What wouldst thou say, child?" asked Mr. Dimmesdale.
"Wilt thou stand here with mother and me, tomorrow noontide?" inquired Pearl.
"Nay; not so, my little Pearl," answered the minister...
Pearl tries to remove her hand from Dimmesdale's grasp, but he holds on and asks her to stay a minute. Once again, Pearl asks Dimmesdale if he will promise to join the little girl and her mother the following day, on the scaffold. Again Dimmesdale says he will not—at least not then. He notes that he will do so another day. When she asks when that day might be, Dimmesdale whispers that they will all stand together on "the great judgment day," before God, but he is clear that he will never do so where people might see them:
...the daylight of this world shall not see our meeting.
Even as fear and agony tear at Dimmesdale's heart and spirit, he cannot conceive of ever exposing his sin to the world. While the quote demands some semblance of the truth, if not the actual sin, Dimmesdale's character is not strong enough to expose what he has done—not even to hint that he has been less than diligent as a servant of God. He is impassioned in his sermons, and sorrowful in his demeanor as if the weight of the world's sins is almost too much to bear. The townspeople might believe he is Christ-like in this way. Ironically, it is his sin that troubles him so—not that of the world. It will not be until he is dying that Dimmesdale will finally confess what he has done, believing there is no forgiveness for him; believing that he will never be joined with Hester and Pearl, not even in Heaven.
[Dimmesdale] consistently refuses to confess his sin (until the end), even though he repeatedly states that it were better, less spiritually painful, if his great failing were known.
The quote may be seen to offer not only a need for truthfulness, but also perhaps the sense that "the truth shall set you free" (in the use of the word "freely"). Dimmesdale is shackled with his guilt until the end, when it appears to destroy him.