On re reading L-Jones' biography, I followed up a ref. to this book and bought it. 2nd hand but perfect and very cheap. It is a treasure chest of reformed/evangelical/charismatic theology. This man has a vast and deep knowledge of history as well as biblical theology (not to mention medicine) One thing he emphasises is that the most powerful source of assurance is the baptism in the holy spirit. This is something that the Puritans knew as well as Whitefield and the Wesleys.