2. Blood and Nerves
There is a very ancient, yet ever new, saying to the effect that the human being is a microcosm. Human beings in the physical world are, in the first place, material phenomena. If we seriously believe that the human being is a microcosm, that our physical being contains the secrets of the whole cosmos, then we will think it worthwhile to examine how our physical being reveals the spiritual. If you study the physical aspect of the human being and think about it and you'll have to think if you strive for knowledge—you will see there are two totally different kinds of substance in our physical being. It only takes ordinary thinking and observation to see that there are two fundamentally different kinds of substance in us: the blood substance, or blood material, and the nerve substance.