John Frith, a Protestant reformer who advocated for religious toleration, was burned at the stake in 1533 due to Henry VIII's desire for a male heir to the throne of England, which led to his break with the Pope who refused to annul his marriage to Catherine of Aragon so he could marry Anne Boleyn. Frith criticized the Pope and Catholic doctrines and was imprisoned in the Tower of London for heresy. Thomas More, Henry's Lord High Chancellor and a staunch Catholic, refuted Frith's arguments in a letter, but Frith responded with this book, written while awaiting execution.