This book is an account of an investigation performed in the Astral Plane by Samael Aun Weor and a group of students.
"One of the most powerful conjurations that King Solomon left us is the “Conjuration of the Seven.” We resolved to personally investigate the entire esoteric content of the “Conjuration of the Seven.” We performed these investigations of High Theurgy within the Superior Worlds. We needed to have complete cognizance of the essential content of that prayer which Solomon the Sage left us in ancient times. Many magicians in the past, as well as in present, utilize these conjurations. However, in order to work consciously with them in the rituals of High Magic, we must understand the meaning of its content. This was the main motive for why we needed to investigate the esotericism of the “Conjuration of the Seven” in depth." - Samael Aun Weor
The Esoteric Treatise of Theurgy (1958) by Samael Aun Weor is included in the compilation The Divine Science.