Another aspect of the veil as a symbol can also be considered regarding "The Minister's Veil": The veil, the thin curtain, is often a guard of privacy, a symbol of a personal struggle to improve and an act of religious devotion [as is the reason for the veil on Islamic women]. With these meanings, the Reverend Hooper's veil is given much significance in Hawthorne's parable of Puritanical hypocrisy a trope that is prevalent in this author's writings. Thus, rather than hiding anything himself, Mr. Hooper may don the veil to signify to his congregation that they need to become involved themselves in the personal struggle to improve and in acts of religious devotion. His wearing of the veil is his act of setting an example for their behavior, for their religious improvement. This is why he tells his fiancee Elizabeth,
Oh! you know not how lonely I am, and how frightened to be alone behind my black veil.
And, it is why he refuses to remove it, crying out on his deathbed,
Tremble also at each other! Have men avoided me, and women shown no pity, and children screamed and fled, only for my black veil?
When it comes to symbolism in literature, many objects, colors and numbers have traditional meanings. These then become applicable each time they are used in something new. Some traditional symbols have meanings rooted in mythology, others in the Bible, others, such as numbers and animals, in ancient Asian traditions.
In this case, the black veil is certainly used as a traditional symbol. The color black is traditionally symbolic of evil, sin, things which are hidden, or sorrow. This is very much a Biblical symbol but is likely rooted in pagan traditions as well.
The fact that the symbolic object is a veil (or cloak, really) that the reverend wears is further suggestive of hidden evil and sin. It is a covering, suggesting that it hides something. It is also a minister who wears it, which certainly would confuse and frighten the congregation in the book as ministers were people to be naturally trusted and respected. However, given the frequency in literature of corruption in the church, this signals to the reader of the story that something evil probably lurks there.
In short, the black veil itself is a very Gothic image, completely traditional in its symbolic nature.