Easter Course IV

What is the cause of the condition that appears as illness? The healthy human being has his head organization, whose structure, even externally, is separated from the rest of the organization. The head is a bony structure in which the brain is enclosed. A continuation of the head is also contained in the bones. The head is self-contained and the rest of the human being is joined to it. But in the finer organization of man there is something that demarcates these two parts of his being. It is not so very easy to prove this fact by external anatomy and physiology, but there is a tremendous amount to be learned by studying the transformation of the foodstuffs, for instance, the fact that these foodstuffs do not, in their own form, pass over into the head organization, nor even into the nerves. There is a sharp boundary line which must not be crossed. What is it that must not cross this boundary?