This book consists of two studies: "Anabaptism and Pietism" and "Mennonite Devotional Literature 1600-1800". The first study gives the general historical analysis, the second provides Friedmann's concrete proof of his thesis. The first treatise puts the question of the Holy Spirit into the center of the discussion, as Friedemann believes that this question is more decisive for the pattern of living Christianity than doctrinal issues. The second treatise attempts to depict the spiritual life in its variform expression showing how the Holy Spirit, or that which sometimes is taken for Him, operates.