Reverend Parris is at best a tormented soul. He believes that everyone wishes to persecute him, even though he does his best to win them over and bring them closer to God.
It is within this context that what he sees in the woods devastates him. He observes a number of girls from the village performing what he believes a ritual to summon spirits in the forest at night. The girls are led by Tituba, the reverend's slave from Barbados. He witnesses her screeching and shouting gibberish and the girls dancing. His young daughter, Betty, and his seventeen-year-old niece, Abigail Williams, are also involved.
Parris jumps from behind a bush to confront them. His daughter is overcome by shock and falls into a deep faint from which she seemingly cannot recover. Reverend Parris summons Doctor Griggs to determine the cause for Betty's condition. He is utterly distraught when he is later informed, through Susanna Walcott, that the good doctor cannot find a cure for Betty's ailment in his books and that the reverend "might look to un-natural things for the cause of it."
This news shocks Reverend Hale and he asks Susanna to inform the doctor that he has already summoned Reverend Hale from Beverley to investigate. He insists that Susanna not make any mention of unnatural causes. The doctor must study further and find a cure in his books.
Abigail tells the reverend that she thinks that there are rumors of witchcraft all about. The reverend, in a heightened state of anxiety, turns on her and demands to know what they were doing in the forest. Abigail confesses that they were dancing for "sport" but were not performing witchcraft. Reverend Hale then mentions that he also saw a dress and thought he saw someone naked running through the trees.
Abigail adamantly refuses to admit to performing witchcraft even though her uncle makes it clear that any such accusations would give his enemies the ideal opportunity to get rid of him. It is soon after this that Reverend Parris is confronted by members of his congregation who are clearly inquisitive about these "unnatural" events.
He has much explaining to do.
Parris came upon the girls dancing in the forest and witnessed Tituba speaking in tongues. He reviews this information in the play's first scene as he is attempting to find a way to avoid a public disaster while also bringing Betty back to health. He is worried that other people will find out.
When Abigail tells Parris that a group of people have gathered downstairs in the house and that he should go speak with them, his response is:
"And what shall I say to them? That my daughter and my niece I discovered dancing like heathen in the forest?"
When Abigail protests and denies wrong doing, Parris continues:
"I saw Tituba waving her arms over the fire when I came on you. Why was she doing that? And I heard screeching and gibberish coming from her mouth."
These items describe what Parris saw and are his reason for suspecting that the girls were up to witchcraft or something like it in the woods. He does not want to believe that this what the girls were doing, however, as witchcraft in his own family would reflect very poorly on him and jeopardize his position in Salem.