This book which lays bare Bunyan's inner life and reveals his preparation for his appointed work is Grace Abounding to the Chief of Sinners (1666). It describes in vivid language and great detail his conviction of sin, his struggles against unbelief, his entrance into the meaning and comfort of the Holy Scripture, and much more that belongs to the realm of Christian experience. It also deals with his call to the Christian ministry, when he preached what he "smartingly did not feel."
John Bunyan (1628 - 1688) was a popular preacher as well as a very voluminous author, though most of his works consist of expanded sermons. In theology he was a Puritan, but not a partisan; nor was there anything gloomy about him. He was no scholar, except of the English Bible, but that he knew thoroughly.