This is an amazing work of writing. This book is a bit "advanced" or may be difficult to understand or intimidating to the beginner Christian. However, it is the christian in those beginning stages who need this most. And that's almost everyone. Father Sattler, through his 6 years isolation, explains who God is, who we are, what sin and evil is, what the interior battle is, and how to live out our earthly lives in preparation for our eternal lives. Most importantly, he explains what prayer truly is, how to pray, and how to abandon self and align your will to only the Will of God. St. Teresa of Avila and St. John of the Cross are the patron saints that greatly assist him in this writing this work.
This book is a treasure, a deep study, and the content in this book alone can be contemplated on for a lifetime. I highly recommend to all Christians.