The son of Richard Mather (1596–1669), who had helped define Congregational orthodoxy in 1648, he became a Boston minister in 1664 and married the daughter of John Cotton. He was a conservative President of Harvard College (1685–1701) but as colonial agent in London (1688–92) he negotiated a liberal royal charter for the state of Massachusetts. On his return he helped end the Salem witch trials. He was a forceful preacher against “declension” (spiritual decline) as well as a prolific author, and was the foremost minister of his generation.