tes to
which our senses are fitted to respond--a sudden drop from billions in
the case of the eye to millions in touch, and to thousands or even tens
in hearing. This makes one wonder whether there are not many things in
nature which man has never discovered simply because he has not the
sense mechanism enabling him to become conscious of their existence.
There are undoubtedly "more things in heaven and earth than are dreamt
of in our philosophy."

DEPENDENCE OF THE MIND ON THE SENSES.--Only as the senses bring in the
material, has the mind anything with which to build. Thus have the
senses to act as messengers between the great outside world and the
brain; to be the servants who shall stand at the doorways of the
body--the eyes, the ears, the finger tips--each ready to receive its
particular kind of impulse from nature and send it along the right path
to the part of the cortex where it belongs, so that the mind can say, "A
sight," "A sound," or "A touch." Thus does the mind come to know the
universe of the senses. Thus does it get the material out of which
memory, imagination, and thought begin. Thus and only thus does the mind
secure the crude material from which the finished superstructure is
finally built.

CHAPTER IV

MENTAL DEVELOPMENT AND MOTOR TRAINING

Education was long looked upon as affecting the mind only; the body was
either left out of account or neglected. Later science has shown,
however, that the mind cannot be trained _except as the nervous system
is trained and developed_. For not sensation and the simpler mental
processes alone, but memory, imagination, judgment, reasoning and every
other act of the mind are dependent on the nervous system finally for
their efficiency. The little child gets its first mental experiences in
connection with certain movements or acts set up reflexly by the
pre-organized nervous system. From this time on movement and idea are so
inextricably bound together that they cannot be separated. The mind and
the brain are so vitally related that it is impossible to educate one
without performing a like office for the other; and it is likewise
impossible to neglect the one without causing the other to suffer in its
development.

1. FACTORS DETERMINING THE EFFICIENCY OF THE NERVOUS SYSTEM

DEVELOPMENT AND NUTRITION.--Ignoring the native differences in nervous
systems through the influence of heredity, the efficiency of a nervous
system is largely dependent on two