In these 8 lectures, Rudolf Steiner focuses on the relationship these forces have with the organs of the body. More specifically, he refers to the organs that make up our digestive and respiratory systems, the importance of "warmth" in the function of the blood, and its effects on the Ego and the inherent evolutionary process in the formation of the spine and brain. These texts, 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 gathering more data on the science of the Grail.