Interpet the description of the following passage, explaining why Hawthorne uses the word "uncertain." "which bore the likeness of a great black...

Nathaniel Hawthorne, the great Early American writer, is responsible for introducing the symbolism that became a signature element of the American novel.  Such a symbolic presence is the old man in "Young Goodman Brown" who accompanies Goodman Brown into the forest primeval. As he leaves his wife Faith, Goodman beholds "the figure of a man, in grave and decent attire, seated at the foot of an old tree."  This man has a staff which "bore the likeness of a great black snake" that seems to wriggle and twist "like a living serpent," but this could be simply a result of the "uncertain light."

Hawthorne uses these words to reflect the "uncertain light" of Goodman Brown's faith.  When confronted by "he of the serpent," Goodman tells him,

I have scruples touching the matter thou wot'st of...my father never went into the woods on such an errand, nor his father before him.  We have been a race of honest men and good Christians since the days of the martyrs...

Goodman Brown questions his convictions, else he would not have bid Faith goodbye and embarked on his journey.  When confronted by evil, he fears that his faith will not hold him in stead; thus, he wishes to withdraw.  It is Goodman Brown who is uncertain, not the light that reflects upon the staff.

Undeterred by his refusal, the "elder person" tells Goodman that he helped his grandfather at the Salem Witchcraft trials as well as assisting his father in the burning of an Indian village.  The old man recognizes the hypocrisy of the Brown family, their uncertainly as true Christians.  As they venture forth, he laughs at Goodman Brown, saying, "prithee, don't kill me with laughing."

Of course, as the story ends, there is an uncertainly to Brown as he is not sure whether he has dreamed or actually witnessed a black mass in the forest.  When his Faith runs to him, he rejects his wife and his figurative Faith as well.  He then becomes "a sad, a darkly meditative, a distrustful, if not a desperate man" for the remainder of his life.  Hawthorne, in his castigation of the precepts of Puritanism, implies the Biblical allusion of faith not being enough to save a person:

Thus also faith by itself, if it does not have works, is dead.   (James 2:17)

Here the Calvinist precept of "Once saved, always saved" is questioned by Hawthorne who was chagrined by the hypocrisy of the Puritans who punished others, but hid their own "secret sins."