High Quality Content by WIKIPEDIA articles! The possession of Elizabeth Knapp of Groton, Massachusetts was documented by Samuel Willard, a prominent preacher in the Puritan, Massachusetts Bay Colony from October 30, 1671 until January 12, 1672. More significantly, Willard sent letters to the Puritan minister Cotton Mather who published an account of Elizabeth Knapp`s possession in his Magnalia Christi Americana.