Answer:
The victims must be believed.
Step-by-step explanation:
Judge Danforth is saying that because witchcraft is an invisible crime, it can only be brought to trial based on verbal testimonies, and because a witch will not testify against herself, the victims' testimonies must be believed. Danforth also assumes that the witches will confess to their crimes after the victims testify. (In reference to The Crucible).