HERE is a link to 151 of his poems/hymns, which are also worth the time to read, bit by bit.
As I read through a few of his letters yesterday, it stood out to me how every line, every word that he wrote was purposeful. His letters do not begin "Hi! How are you?" No. They start off deep, intense, and personal. He is intentional to take every bit of space on the paper he is writing on to turn the reader to Christ. To the reality of life in this world. To the blessedness of perseverance, or to the desperate need of repentance. He seems to fear no one in his writing. Newton was bold for Christ.
As I read through some of his letters, a deep desire came over me to make my own words count. To be intentional in my letters. To be bold for Christ. To be intentional with my spoken words. Recently we heard a sermon at our church that reminded us of the need to live godly lives. I listened to two other messages by different preachers on the same passage to fill it out a little for myself, and the main point i heard? EVERYTHING we do while we traverse this planet matters. Everything. Every word spoken. Every act of love. Every sacrifice made for Christ. Every time we say NO to sin. Every time we choose self-control (by the power of His Spirit) over blowing our top. Every time we make a conscious choice not to gossip. Every time we fold another.load.of.laundry. Every time we get up early to have those precious moment with our Saviour. Everything matters. Everything.

John Newton seemed to understand this. His letters reflect it. His poetry and his hymns proclaim it. In the midst of his own pain and difficulties, the Gospel shines forth as the most beautiful Light, calling us all to fix our gaze on Jesus Christ, the Author and Perfector of our faith.
Whatever you do, do your work heartily, as for the Lord rather than for men, knowing that from the Lord you will receive the reward of the inheritance. It is the Lord Christ whom you serve. Colossians 3:23-24