"The Minister's Black Veil" has puzzled readers and critics since it was published in 1836 because Hawthorne does not make it clear what Reverend Hooper's reasons were for wearing the veil. Reverend Hooper's own statements, however, at the beginning of the story and on his deathbed, provide us with at least an appropriate, if not the only, answer.
On the morning when Reverend Hooper appears wearing the veil, he gives a sermon in church in which the "subject had reference to secret sin, and those sad mysteries which we hide from our nearest and dearest, and would fain conceal from our own consciousness, even forgetting that the Omniscient can detect them." In other words, Hooper's sermon reflects his belief that all people, no matter how outwardly good they appear to be, hide their innermost thoughts (and perhaps sins) not only from everyone else but also from themselves, and even forget that God can see into their souls. It is reasonable at this point to conclude that the veil may be a symbol of each person's hidden sins. Reverend Hooper seems to be saying that we can never truly know another person because that person's innermost thoughts and feelings are "veiled."
As Reverend Hooper is dying, his final comments on the veil make it more likely that the veil symbolizes man's hidden inner thoughts and feelings: "When the friend shows his inmost heart to his friend; the lover to his best-beloved; when man does not vainly shrink from the eye of his Creator, loathsomely treasuring up the secret of his sin; then deem me a monster, for the symbol beneath which I have lived, and die!" For Reverend Hooper, at least, the veil he wears is the same veil that everyone else wears in order to keep their innermost thoughts, feelings, and sins hidden from others.
One of the problems with Reverend Hooper's wearing of the veil is that his congregation never actually understood the veil's meaning. If Reverend Hooper's goal was to use the veil to convince everyone to disclose their sins to each other, so that they could truly know each other, he failed miserably. In the final analysis, one could argue that Hooper ruined his own life, his fiance's life, and the communal life of his congregation with a symbol that no one actually understood.