by their guise of the reality of external matter.

We find consciousness, then, determined by all past experience, by an
external world, and by its organ of expression--the _brain_.

Consequently, our psychology leads us into anatomy and physiology,
which, probably, we have already fairly mastered. In rapid review, only,
in the following chapter we shall consider the organs of man's
consciousness, the brain, spinal cord, and the senses, and try to
establish some relation between the material body and its mighty
propelling force--the _mind_.

CHAPTER III

ORGANS OF CONSCIOUSNESS

Nothing is known to us until it has been transmitted to the mind by
the senses. The nerves of special sense, of sight, hearing, smell,
taste, touch, the temperature sense ("hot or cold" sense), the
muscular sense (sense of weight and position), these, and the nerves
controlling voluntary motion, form the peripheral, or surface, nervous
system. This acts as a connecting medium between the outside world and
the central nervous system, which is composed of the brain and spinal
cord. We might liken the nerves, singly, to wires, and all of them
together to a system of wires. The things of the external world tap at
the switchboard by using the organs of special sense; the nerves,
acting as wires, transmit their messages; at the switchboard is the
operator--consciousness--accepting and interpreting the jangle of
calls.

The recognition by the brain of the appeals coming by way of the
transmitting sense, and its interpretation of these appeals, is the
mind's function of consciousness, whether expressed by thinking,
feeling, or willing.

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
eat--hunger; 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 imme