In these revealing lectures, Steiner concentrates on the relationship between those forces and the human physical organs. In particular, he discusses the organs that make up our digestive and respiratory systems; the significance of "warmth" in the function of the blood and its effects on the I, or Ego; and the evolutionary process implicit in the formation of the spinal column and brain. He deals with all of this in a scientific way that will appeal equally to doctors and therapists, as well as students of Steiner's spiritual science. These talks--long out of print--are also remarkably accessible to the general reader.