The House of the Spirit is a work on the Art of Corpus, written in 873 by Praetorius of Verditius. It covers human anatomy and the principles of affecting such with magic in great detail. The interested reader soon finds that much of the knowledge of the author was gained via vivisection, sometimes of living subjects; the illustrations found in Praetorius' original manuscript are usually left out by copyists in the name of good taste. Many of Praetorius' tractatus on related subjects are even worse.