The Central And Peripheral Nervous Systems In Action
I am passing the open door of a bake-shop, and a pervading odor fills
the air. I think "hot rolls," because my organ of smell--the nose--has
received a stimulus which it transmits along my olfactory nerves to the
brain; and there the odor is given a name--"hot rolls." The recognition
of the stimulus as an odor and of that odor as "hot rolls" is
consciousness in the form of thinking. But the odor arouses desire to
unger; and this is consciousness in the form of feeling. The
something which makes me walk into the shop and buy the rolls is
consciousness in the form of willing. The sensory appeal from the
outside world gained admission through the sense of smell; this
transmitted the message, and consciousness recognized the stimulus,
which immediately appealed to my hunger and incited action to satisfy
The ear of the operator in the telegraph office, again, might illustrate
consciousness. It must be able to interpret mere clickings into terms of
sense. To the operator the sounds say words, and the words are the
expression of the object at the other end of the wire. The brain is the
receiving operator for all the senses, which bring their messages in
code, and which it interprets first as sound, vision, taste, touch,
feel, smell, temperature; then more accurately as words, trees, sweet,
soft, round, acrid, hot.
The mind can know nothing except as the stimulus is transmitted by
sense-channels over the nerves of sense, and received by a conscious
brain. A baby born without sight, hearing, taste, smell, or touch would
remain a mere bit of clay. He could have no awareness. But so long as
any one sense channel remains open the mind may acquire some knowledge.
Suppose I am paralyzed, blind, and deaf, and you put a tennis-ball into
my hand. I cannot tell you what it is, not even what it is like. It
means nothing whatever to me, for the sense channels of touch, sight,
and hearing, through which alone it could be impressed upon my brain,
are gone. Suppose I am blind and deaf, but have my sense of touch
intact; that I never saw or touched or heard of a tennis-ball before,
but I know "apple" and "orange." I can judge that the object is round,
that it is about the size of a small orange or apple. It is very light,
and has a feel of cloth. I know it to be something new in my experience.
You tell me in the language of touch that it is "tennis-ball"; and
thereafter I recognize it by its combination of size, feel, and weight,
and can soon name it as quickly as you, who see it.
Suppose I am blind and my hands are paralyzed, but I have my hearing.
You tell me this is a tennis-ball, and if I have known "tennis-ball" in
the past, I can describe it to you. It has been impressed upon my brain
through my sense of hearing; and memory immediately supplies the
qualities that go with "tennis-ball."
But if none of the senses has ever developed, my brain can receive no
impression whatever; it cannot have even the stimulus of memory. Hence
conscious mind cannot be, except as some sense-channel or channels have
been opened to carry thought material to the brain. So far as we know
today, in this world, mind is absolutely dependent upon the sense organs
and the brain--upon matter--for existence.