By Dr Oliver Tearle (Loughborough University)
Published in 1678 and begun while its author John Bunyan was in prison, The Pilgrim’s Progress is one of the most influential books in the English language. After the Bible (in various English translations), it’s thought to be the biggest-selling book in English: one count, from 1692, just fourteen years after the book’s first publication put the number of copies sold at 100,000: a huge number by seventeenth-century standards.