The Great Gain of Godliness

Thomas Watson is one of the most famous Puritan preachers in history, and his writings during the 17th century are still read across the world today. He was a prodigious writer whose works include All Things for Good (originally published as A Divine Cordial), The Ten Commandments, and more.
The Great Gain of Godliness was Watson's study of Malachi 3:16-18, and it was considered so influential among past generations that no less than Charles Spurgeon once bemoaned the fact he couldn't find it. Spurgeon told his scholars, "This volume would be a great find if we could come at it, for Watson is one of the clearest and liveliest of Puritan authors. We fear we shall never see this commentary, for we have tried to obtain it, and tried in vain."