ts way about. Helen Keller's brain, as shown by her
accomplishments in later life, was a remarkable one; not long after birth
she became deaf and blind, consequently there was practically only one
avenue of intelligence left open for the education of that brain, viz. the
tactile kinaesthetic. But the tactile motor sense is the active sense that
waits upon and contributes to every other sense. The hand is the instrument
of the mind and the agent of the will; consequently the tactile motor sense
is intimately associated in its structural representation in the brain with
every other sense. This avenue being open in Helen Keller, was used by her
teacher to the greatest possible advantage, and all the innate
potentialities of a brain naturally endowed with remarkable intellectual
powers were fully developed, and those cortical structures which normally
serve as the terminal stations (_vide_ fig. 16) for the reception and
analysis of light and sound vibrations were utilised to the full by Helen
Keller by means of association tracts connecting them with the tactile
motor central stations. The brain acts as a whole in even the simplest
mental processes by virtue of the fact that the so-called functional
centres in the brain are not isolated fields of consciousness, but are
inextricably associated one with another by association fibres.

THE PRIMARY REVIVAL OF SOME SENSATIONS IN THE BRAIN

I have on page 77 referred to Stricker's views on the primary revival of
words in the sense of movement of the lips and tongue. Mach ("Analysis of
the Sensations") says: "The supposition that the processes in the larynx
during singing have had something to do with the formation of the tonal
series I noticed in one of my earlier publications, but did not find it
tenable. Singing is connected in too extrinsic and accidental a manner with
hearing to bear out such an hypothesis. I can hear and imagine tones far
beyond the range of my own voice. In listening to an orchestral performance
with all the parts, or in having an hallucination of such a performance, it
is impossible for me to think that my understanding of this broad and
complicated sound-fabric has been effected by my _one_ larynx, which is,
moreover, no very practised singer. I consider the sensations which in
listening to singing are doubtless occasionally noticed in the larynx a
matter of subsidiary importance, like the pictures of the keys touched
which when I was more in pract