The same is true of words spoken in the same room with the hearer, even spoken directly into the ear. No external word, no external sound, ever reaches the brain. There is no external sound. The only sounds ever heard in any brain are cognitions originating and existing only in the brain—cognitions of internal relations in the brain produced by correlative external relations through energy transmitted to the brain through the ear and auditory nerve fibers.
The ear and the auditory nerve fibers reaching from it to the brain are the counterpart, mechanically and functionally, of the telephone and the wire reaching from Denver to San Francisco. This is also true of vision. We may truly say that what the eye sees is not what the eye sees, but what the brain takes cognition of within itself. All vision is cognition originating and existing only in the brain, cognition of internal relations produced in the brain by correlative external relations transmitting energy to the brain through the visual tract, that is, the eye and optic nerve-fibers.
All sensations are purely physiological phenomena, cognitions produced by external relations transmitting energy to the brain through sensory tracts. Our cognitions of the relations of physical elements constitute the sum of human knowledge. There are undoubtedly many relations and combinations, of which we have no cognitions, no knowledge. When some new instrument extends the range of our senses, so that we become cognizant of these combinations, we call them phenomena.
We appear to have no power of dealing with, of considering, discussing or even contemplating anything but cognitions. In a physical sense we may handle portions of the Universe. We may impress upon portions of the Universe the power of intelligence and will to produce or prevent changes of condition, but intellectually we are able to deal only with cognitions of successive states of the Universe or portions of it, not with the actual physical elements themselves. For example, through the exercise of intelligence and will we may cause the human hand to manipulate a lever, which, through a suitable mechanism, will cause a revolving shaft to increase or decrease in its speed or rate of revolution. But we cannot contemplate either the shaft, its changes of speed or the mechanism.
All we are able to contemplate is our cognitions of them, not the things themselves. All cognitions exist in the brain only, but the external objects or influences which produce cognitions are located at the point of contact or irritation of the nerve with the external influence. For example, an injury to the finger, through a nerve-fiber extending from the point of injury to the brain, causes in the brain the cognition of the sensation of pain, but the cause of the cognition is located at the point of injury, the finger, and the brain locates the sensation at that point. The same is true of all cognitions of external happenings, that is, all cognitions of sensation. All other cognitions, such as memory, thought, desire, originate in the brain.
***Excerpt from Charles John Reed: The Law of Vital Infusion and the Phenomenon of Consciousness