Diabology is a rather extensive work of demonology, although that is not the only subject. Indeed, it concerns itself with everything dark within the Christian spiritual framework and, naturally, thus the contrasting opposites of those same things and ideas; for the demon there is an angel, for Satan a God, and so forth. Altogether the work is quite dense as well, and it is much more an academic guide than a casual work. It is most interesting, perhaps, for its treatment of the very nature of good and evil based on the Bible, and elaborates at quite a lot of length on how this informs the Christian view of demons, including from a linguistic point of view.
It should be noted that some footnotes were omitted because they merely replicated quotations in the main work itself in German or Greek. I retained the Latin because it is interesting.