I. Soul and Spirit in the Human Physical Constitution

In studying the human being, only those elements which can be pictured as solid, or solid-fluidic, are regarded as belonging to his organism. It is, of course, acknowledged that the fluid and the airy elements pass into and out of the human being, but these are not in themselves considered to be integral members of the organism. The warmth of the organism which is greater than that of the environment is regarded as a state or condition of the organism, but not as an actual component. We shall see what I mean by saying this. I have already drawn attention to the fact that when we study the rising and falling of the cerebral fluid through the spinal canal, we can observe a regular up-and-down oscillatory movement caused by inhalation and exhalation; when we breathe in, the cerebral fluid is driven upwards and strikes, as it were, against the brain; when we breathe out, the fluid descends. These processes in the purely liquid components of the human organism are not considered to be part and parcel of the organism itself. The general idea is that, as a physical structure, the human organism consists of the more or less solid, or at most, solid-fluid substances found in it. It is generally pictured as a structure built up from these more or less solid substances (Illustration I).