The necessity for an historical-critical edition of the letters of Philipp Jakob Spener became evident in the course of Pietism research.
As a supplement to existing printed works, such an edition is an indispensable resource for research into the historical development of Pietism.
Two undertakings above all were necessary for such an edition of letters:
- Supplementing the already printed letters with those still in manuscript.
- An historical-critical treatment of the letters, as well as an historical commentary, which in many cases requires the identification of the addressees and an exact dating of the letters.
Johannes Wallmann, at the time Professor for Modern Church History at the Ruhr University Bochum and a proven authority on Orthodoxy and Pietism, presented a detailed justification of, and concept for this project. He then was commissioned by the Historical Commission for Research in Pietism to realize it.
Added to these are
- several letters from his Strasbourg period
- the correspondence with August Hermann Francke, and
- the correspondence with Adam Rechenberg.