of the origin and nature of the soul is solved by phylogenetic psychology. The human soul is evolved from a long series of other mammalian souls. The historical evolution of the human soul out of a long series of higher and lower mammalian souls must be regarded as a scientifically proved fact.
Consciousness is a natural phenomenon like all the other soul activities. Consciousness is inner intuition, perception, Anschauung, an inner reflection or mirroring. We may divide it into world-consciousness and self-consciousness. The former embraces all possible phenomena of the external world which are possible to our knowledge; the latter is an inner mirroring of our own soul activity, of all ideas, sensations, strivings, and will acts. Consciousness and psychical life are not identical; psychical life extends farther than consciousness. Unconscious sensations, ideas and impulses also belong to soul life; indeed, this field is larger than the other.
Consciousness is bound to a centralized nervous system. The presence of a nervous central organ, highly developed sense-organs and association-groups, is essential to the existence of unitary consciousness. Protists have no developed ego-consciousness; their sensations and movements are unconscious. In short there is no consciousness until we reach the higher animals. The elementary psychic activities are all unconscious. The riddle of consciousness is no riddle at all. The neurological problem of consciousness is only a special case of the all-embracing cosmological problem, of the problem of substance. The problem of consciousness is a physiological problem, and as such to be reduced to the phenomena of physics and chemistry. Consciousness is therefore only a part of the higher soul activity, and as such dependent upon the normal structure of the corresponding soul organ, the brain. It is absolutely dependent upon the chemical changes of the brain substance. It is not an immaterial being, but a physiological function of the brain. The new-born child is without consciousness; consciousness is a late development, arising first when the child learns to talk.
With the death of man all physiological activities cease, and with them the 'soul,' that is, that sum of brain functions which psychical dualism regards as a separate being, independent of the other manifestations of the living body. The protozoa are just as mortal in the physiological, and hence also in the psychological, sense as the metazoa. Energy and matter are inseparably connected. We distinguish between the psychical energy (sensation, presentation, willing) and psychical
- 'Weltraethsel,' pp. 197ff. See also 'Monismus,' pp. 22f.