THE "PILING UP" OF CONSCIOUSNESS IS ATTENTION.--This figure is not so true as the one which likens our mind to a stream with its ever onward current answering to the flow of our thought; but whichever figure we employ, the truth remains the same. Our mental energy is always piled up higher at one point than at others. Either because our interest leads us, or because the will dictates, the mind is withdrawn from the thousand and one things we might think about, and directed to this one thing, which for the time occupies chief place.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.
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.