might think about, and directed to this one
thing, which for the time occupies chief place. In other words, we
_attend_; for this piling up of consciousness is nothing, after all, but
attention.

3. CONTENT OF THE MENTAL STREAM

We have seen that our mental life may be likened to a stream flowing now
faster, now slower, ever shifting, never ceasing. We have yet to inquire
what constitutes the material of the stream, or what is the stuff that
makes up the current of our thought--what is the _content_ of
consciousness? The question cannot be fully answered at this point, but
a general notion can be gained which will be of service.

WHY WE NEED MINDS.--Let us first of all ask what mind is for, why do
animals, including men, have minds? The biologist would say, in order
that they may _adapt_ themselves to their environment. Each individual
from mollusc to man needs the amount and type of mind that serves to
fit its possessor into its particular world of activity. Too little mind
leaves the animal helpless in the struggle for existence. On the other
hand a mind far above its possessor's station would prove useless if not
a handicap; a mollusc could not use the mind of a man.

CONTENT OF CONSCIOUSNESS DETERMINED BY FUNCTION.--How much mind does man
need? What range and type of consciousness will best serve to adjust us
to our world of opportunity and responsibility? First of all we must
_know_ our world, hence, our mind must be capable of gathering
knowledge. Second, we must be able to _feel_ its values and respond to
the great motives for action arising from the emotions. Third, we must
have the power to exert self-compulsion, which is to say that we possess
a _will_ to control our acts. These three sets of processes, _knowing_,
_feeling_, and _willing_, we shall, therefore, expect to find making up
the content of our mental stream.

Let us proceed at once to test our conclusion by introspection. If we
are sitting at our study table puzzling over a difficult problem in
geometry, _reasoning_ forms the wave in the stream of consciousness--the
center of the field. It is the chief thing in our thinking. The fringe
of our consciousness is made up of various sensations of the light from
the lamp, the contact of our clothing, the sounds going on in the next
room, some bit of memory seeking recognition, a "tramp" thought which
comes along, and a dozen other experiences not strong enough to occupy
the center of the field.

B