The Pseudomonarchia Daemonum is an appendix to a book on demons and the occult published in 1577 by Johann Weyer. The original Latin and an English translation is just sitting there online for you to browse to learn all about spirits, eldritch gods, demons and other magical creatures, like Bael (pictured above), the ancient Phoenician god who is one of the seven princes of Hell. Turns out Bael appears as a three-headed beast with a spider’s body and who commands legions of devils. Pretty neat.