What was Cotton Mather's role in the Salem witch trials?

Cotton Mather was a Puritan minister and one of the most interesting characters in American history. Mathers was the son of a well-established Massachusetts family. His academic prowess was noted at an early age. Mathers was fluent in Greek and Latin by the age of twelve. At age eighteen, he earned a master's degree from Harvard, where his father served as president.
Cotton Mather was an enigma. Though deeply religious, Mather had a passion for science and at one time considered the field of medicine as a possible vocational choice. Historians believe Mather was a stutterer and thought his speech was too much of an impediment to preach to a congregation. Through hard work and practice, Mather overcame his speech impediment and began a career as an ordained minister in 1685. He served in the role of a minister for forty years.
Mather was an enigma. In many ways, he was extraordinarily forward-thinking and progressive for men of his time; at other times, he was deeply rooted and stubborn in religious matters. He promoted public education and education reform. One of the education reforms he promoted is that schools should use rewards instead of punishment to motivate students.
In science, Mather saw the threat that smallpox presented. While others in the medical and scientific community held steadfast to anachronistic treatments held over from the sixteenth century, Mather actively promoted the idea of vaccination. Needless to say, the dignified members of the community were appalled. To prove the effectiveness of his approach, he inoculated his son, further distancing himself from the established medical community's idea of how smallpox should be treated. From the pulpit, he was known as a defender of the traditional Christian values associated with the times he lived in, but he drew the ire of government officials when he included criticism of them in his sermons.
Cotton Mather has the unique distinction of being one of the main instigators of the witch hysteria that resulted in the Salem Witch Trials. Mather believed, like many people steeped in the religion of the day, that some individuals had traded their souls to the devil in exchange for the powers associated with witches or sorcerers. In 1689, Mather published Memorable Providences, Relating to Witchcraft and Possession. The publication was widely distributed and read. Much as Uncle Tom's Cabin spurred people to think about ending the tragedy of slavery, historians believe that Mather's stature in the community and this publication resulted in an active interest in rooting out witchcraft. Mather lent his credibility to arresting and prosecuting witches. He was very supportive of the judicial punishment for accused witches and had little problem with trusting hearsay evidence against the accused.
Cotton Mather was a brilliant, forward-thinking person of science, on the one hand; paradoxically, he was also very comfortable with using unscientific and nonempirical data in his pursuit to persecute people believed to have made a covenant with the devil.