In these 8 lectures, Rudolf Steiner focuses on the relationship that these forces have with the organs of the body. Specifically, he refers to the organs that make up our digestive and respiratory systems, the importance of "warmth" in the functioning of the blood, and its effects on the ego and the inherent evolutionary process in the formation of the spinal column and the brain. These texts, which are presented in a scientific manner, are addressed to doctors, therapists, and students of Rudolf Steiner's spiritual science, as well as to the uninitiated who are simply interested in collecting more data about the science of the Grail.