The phrase "lo! On every visage a Black Veil!" can be found towards the end of Nathaniel Hawthorne's Gothic story "The Minister's Black Veil", when Minister Hooper is on his deathbed and being persuaded by Reverend Clark to remove the black veil that had been covering his face for a long period of time now, causing fear and discomfort in his community.
Reverend Hooper rejects the proposition. He argues that it is interesting how he mystery of what the veil "could" be hiding is actually what drives men, women, and children away; that, if people did not have a naturally wicked mind which incites them to think and wonder about the wickedest things, they would see that the piece of clothing is merely what it is: a piece of black crepe. It is the soiled conscience and imagination of humanity what gives it a bad meaning.
Moreover, Reverend Hooper opens up about what the people around him may be hiding, not behind a piece of black crepe, but behind a kind face, or a fake smile, or a well-created kind personality. In all, Rev. Hooper makes everyone aware of one thing: everybody wears a mask, and our faces are merely that mask beneath which anything lurks. And some people hide behind that mask some horrid and evil things that no one would ever suspect. However, how hypocritical it is from the parishioners to fear a piece of clothing: could it be that, deep inside, we all fear the things we each hide from society? Hence, Rev. Hooper further says
"Why do you tremble at me alone? Tremble also at each other!"..."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...I look around me, and, lo! on every visage a Black Veil!
Concisely, Rev. Hooper makes an open accusation to every sanctimonious or hypocritical man or woman in society and reminds them that everybody, in all, wear a veil of lies and secrets.