Nathaniel Hawthorne's study of good and evil in humanity in Young Goodman Brown implies there is evil lurking in the breasts of all human beings. Goodman Brown does not believe the pious individuals he knows in his Puritan community are capable of evil. One night in the woods, he encounters what appear to these pious individuals involved in satanic rituals. He encounters the Devil, who informs him he is "well acquainted" with his ancestors (Hawthorne, 1835, p. 2). Goodman Brown refuses to believe people like the town Deacon and Goody Cloyse, who taught him catechism, are capable of prayer, because they are of "a people of prayer, and good works to boot, and [who] abide by no such wickedness" (Hawthorne, 1835, p. 2). When Goodman Brown discovers these individuals are involved in what is considered evil practices, he exclaims "Can this be so" (Hawthorne, 1835, p. 2). When he returns to town the following morning, Brown's faith is undermined and he is in a bewildered state as he looks upon the same people he previously viewed as pious through new eyes. Brown has seen that evil can lurk in the breasts of all people, even those who come off as pious on the surface. As he laments, "My faith is gone! There is no good on earth; and sin is but a name. Come, devil, for to thee is this world given" (Hawthorne, 1835, p. 5). In this sense, Hawthorne may not have been arguing that the nature of human beings is evil or that all human beings give into the temptation of evil. He is arguing; however, that it is the nature of all human beings to have the capacity to act evilly.
Hawthorne, N. (1835). Young Goodman Brown. Retrieved February 10, 2009, from http://pip.shsu.edu/~eng_wpf/authors/Hawthorne/Goodman-Brown.htm
...