But a new edition certainly needed changes. I tried out the title on a friend. "This is what?" was his reply. That title comes from Peter's speech on the Day of Pentecost in Acts 2:16, 'But this is that which was spoken by the prophet Joel' (KJV). It meant something to those familiar with the KJV, but was lost on a newer generation, and sounded odd. So it became The Spirit of Revival. We also credited it to Norman Grubb, the General Secretary of WEC at the time, who undoubtedly edited the material.
The content of the book also suffered from changes in language and culture since the 1950s, so I wrote to Helen Roseveare and asked her to consider writing a new introduction, taking into account various factors that I mentioned to her. She had witnessed the amazing events of the Congo Revival herself as a new missionary. She graciously consented, and what she produced for us was wonderful. Her new introduction dealt with all the aspects I had listed, but also included her own eyewitness account of the revival. It is worth reading by itself.
The book is now out of print, but still available from the publisher, Christian Focus, and used copies via several resellers. A book exists in print with the same title about the work of Jonathan Edwards; don't be confused by that!