The Quakers -- or “Children of the Light” and “Friends of the Truth”, as they would have called themselves at the time -- were one of many radical sects that sprang up in the turbulent 1640s. Refusing to fight for either side in the English Civil War -- the beginning of their pacifist beliefs -- the Friends espoused a radical egalitarianism; “The Divine Light”, as Ellwood explains, “is equally in all”. Within a few years of its founding, women and minorities had achieved positions of authority within the movement.

George Fox, the founder of Quakerism, believed that it was possible to have direct, individual communion with God, without the necessity for clergy, sacraments, or a Church hierarchy. Quakers to this day ordain no ministers, and are more mystically-focussed than other Protestant denominations. A traditional Quaker meeting has no formal worship leader, and begins in silence, with the congregation waiting for God's spirit to move individual worshippers to pray, sing or testify.

In the 17th century, Quakers most visibly eschewed all outward signs of status in dress and deportment. They did not bow to any man, refused to remove their hats in church or court, and used the informal, intimate “thee” and “thou” form of address even to their social superiors, many of whom were insulted by the Quakers' perceived lack of respect.

Quakers also refused to swear oaths, insisting that their duty was to speak truth in all situations and that the ritual of oath-taking implied that they did not always live up to this standard. This caused some difficulty, as Quakers often were not allowed to bear witness in court, and were prevented from entering in to certain business arrangements.

The Friends were harassed, largely for these peculiarities, throughout the 1650s and 1660s. By the 1670s the official attitude had hardened into genuine persecution. Ellwood himself, as described in the play, was first gaoled in 1665, and over the next decade would be arrested and imprisoned several more times. Eventually, to relieve the pressure on the group, William Penn led a number of English Quakers to the new world, eventually settling in the New England colony which still bears its founder's name.

Quakers were among the first and staunchest agitators for the abolition of Slavery, advocated on behalf of Native Americans, lent their early support to the Feminist and Civil Rights movements. Many of the world's most famous and influential companies and advocacy groups -- among them Greenpeace, OXFAM and Amnesty International -- trace their roots to the Quaker movement. Quaker churches have been among the first mainstream Christian denominations to celebrate marriages for same-sex couples.