I cannot highly enough recommend this book to the attention of my fellow Christians. I have read it a few times now, and it has not failed to move me powerfully each time, to grow me in grace, to enrich my understanding, to strengthen my faith.
If you have a tender conscience, if you struggle with guilt, if you desire to better understand your position in Christ, if you desire to better understand the work and role of the Holy Spirit in the life of a believer, if you like to contemplate the glories of heaven or the marvelous free grace of the Savior, if you seek assurance of salvation or long to know more about the certainty of God's work in His people, this is the book for you.
The work is a pastoral exposition of 2 Corinthians 3:17-18. Every word is full of grace and truth and life. My copy is more underlined than not.