Feb 18 John Bunyan's Pilgrims Progress

Today in 1678 puritan preacher John Bunyan published an allegory called The Pilgrim's Progress from This World, to That Which Is to Come. Commonly known by the shorter title 'The Pilgrims Progress' Some people consider it to be the first novel in English. It has since been translated into more than 200 languages, and has never been out of print, reputedly making it the bestselling book after the Bible. Why has it been so successful? How did he write it? How did it spread internationally? and why is it linked to the Taiping Rebellion in China?