This book by Canadian Grant Gordon explores the relationship between John Newton (1725-1807) and George Whitefield (1714-1770). I can't remember reading a book exactly like this but it certainly works well in that it sheds light both on Newton and Whitefield and is very stimulating to thought. I suppose when you read a single biography you identify or fail to identify and there can be no easy way to apply the lessons learned. This format means that you are forced to stand back and consider two pretty different men - not even exact contemporaries (they only knew each other the last 15 years of Whitefield's life) - and so the danger of over identifying is not really there in the same way,
The approach is to briefly give the two men's lives up to 1754 then in five chapters look t the life of Newton and his interactions with Whitefield. Closing chapters consider Whitefield's impact on the younger man and how they compare and contrast with a final page or two on Newton's final tribute to Whitefield. If you know the story of Newton and Whitefield you will enjoy the way they are delineated that much more sharply by this book.
Dr Grant intimated that he intends a similar book on Newton and Wesley which would be very welcome. This present volume is enhanced by several visual items, an index, etc. It is a pity it is not in hardback.