"Essay on Incubus, or Nightmare" is the work of the famous author John Bond, a doctor and researcher of medical phenomena. In this book, the author examines the phenomenon of the incubus, a terrible dream that torments a person at night. Analyzing a variety of incubus cases, he offers his deep knowledge and thoughts on the subject. The book is an important resource for understanding dreams, the psychosomatics, and the medical aspects of nightmares. Readers will find in this work interesting conclusions and opinions that remain relevant even today.