Isaac Penington was born in London, England in 1616. His father was the Lord Mayor of London and a Puritan. Penington married a widow named Mary Springett and together they had five children. At the age of 42, Penington and his wife became Quakers after hearing George Fox preach in Bedfordshire, England. An extensive writer, Penington proved to be a valuable asset to the Quaker community. He was arrested six times for his beliefs. Penington's stepdaughter, Gulielma Springett married William Penn. He died in October 1679.
Michael Walsh (ed.). Dictionary of Christian Biography. The Liturgical Press. 2001.