John Hale, the minister at Beverly in Essex County, had been a close observer of the Salem witch crisis and supported the court's literal interpretation of spectral testimony into the fall of 1692. However, when seventeen-year-old Mary Herrick accused Hale's own wife of afflicting her in spectral form, he began to rethink his position. Hale came to realize that spectral evidence was indeed unreliable and that innocent blood had been shed; he blamed himself for “unwittingly encouraging…the Sufferings of the innocent.” In the aftermath of the witch hunt, a number of figures involved in the trials acknowledged in public their sense of personal guilt. Twelve jurymen signed an open letter of apology in which they admitted that they had been “sadly deluded and mistaken.” In early 1697, on a fast day commemorating “the late tragedy,” Samuel Sewall, one of the court magistrates, had his minister Samuel Willard read from the pulpit a statement in which Sewall accepted “blame and shame” for his role in the proceedings, “Asking pardon of men, And especially desiring prayers that God…would pardon that sin and all other his sins.” John Hale decided to express his contrition rather differently. By the end of 1697, he had decided to write a treatise on witch trials, the purpose of which was to ascertain “How Persons Guilty of that Crime may be Convicted.”