Page:Popular Science Monthly Volume 27.djvu/169

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THE NERVOUS SYSTEM AND CONSCIOUSNESS.
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less the characteristics of consciousness, as we know them and are obliged to know them, resemble the characteristics of brain-activity as we know them and are obliged to know them. It will not avail to say there are striking differences between heat, electricity, and light; there are striking resemblances—one positive, constant resemblance—they are all modes of motion. Between the characteristics of consciousness and the characteristics of nerve-matter, as we know them, there are no resemblances whatsoever. If the smaller physiological materialists (for the larger do it fully) would but think it worth their while, and a truly scientific procedure, to fasten their attention upon consciousness, they might be struck by its peculiarities. The distinctive features of consciousness in general have often been indicated. I shall restate them here as they have been compared with nerve-activities, arranging them in pairs for the sake of clearness:

     1. Nerve-activities:
All are modes of extension and motion.
Consciousness-activities:
None can be conceived as extended or moving.
2. Nerve-activities:
They may be observed through the senses.
Consciousness-activities:
They are never known through the senses.
3. Nerve-activities:
They are external to the observer.
Consciousness activities:
They are internal to the observer.
4. Nerve-activities:
Each may be directly seen at the same time by many observers.
Consciousness activities:
They can be directly known by one person only, viz., he who experiences them.
5. Nerve-activities:
They consist of parts external to each other and are divisible.
Consciousness-activities:
They have no distinction of parts and are indivisible.

It may surprise some readers to be told that this contrast is fully recognized by many leading upholders of evolution. Mr. Spencer says, "There lies before us, in the study of consciousness, a class of facts absolutely without any perceptible or conceivable community of nature with the facts that have occupied us in the study of the nervous system."

Dr. Tyndall ("Address on Scientific Materialism," Norwich) says: "The passage from the physics of the brain to the corresponding facts of consciousness is unthinkable. The chasm between the two classes of phenomena is intellectually impassable." Professor Huxley says: "I know nothing whatever, and never expect to know anything, of the