This is a deep, spiritual devotional book written by a 17th century French nobleman. Despite Fenelon's sometimes unorthodox views, I believe all Christians can benefit greatly from this text. It really is on another level from most Christian books and people you would meet in today's world.
Fenelon emphasizes detachment from the world, and an utter abandonment of self-will in favor of God's will. Really, it is a reorienting of our own will with God's. I suggest reading a passage or two each day (lectio divina), praying and contemplating the passage to make it more than words in the mind, but that it becomes integrated with who we are.
If Christians would undertake such a discipline each day, and try to consciously determine whether each thought and action is in conformity with God's will for their lives, this world would be dramatically transformed, just as it was in the days of the early disciples.