sucked. Some day it will occur to him that that fist belongs to
the same being who owns the sucking mouth. But at this point, Miss
Shinn[C] has observed, the baby is often surprised and indignant that
he cannot move his arms around and at the same time suck his fist.
This discomfort helps him to make an effort to get his fist into his
mouth and keep it there, and this effort shows his will, beginning to
take possession of his hands and arms.

[Sidenote: Growth of Will]

Since any faculty grows by its own exercise, just as muscles grow by
exercise, every time the baby succeeds in getting his hands to his
mouth as a result of desire, every time that he succeeds in grasping
an object as result of desire, his will power grows. Action of this
nature brings in new sensations, and the brain centers used for
recording such sensations grow.

As the sensations multiply, he compares them, and an idea is born. For
the beginnings of mental development no other mechanism is actually
needed than a brain and a hand and the nerves connecting them. Laura
Bridgeman and Helen Keller, both of them deaf and blind, received
their education almost entirely through their hands, and yet they
were unusually capable of thinking. The child's hands, then, from the
beginning, are the servants of his brain-instruments by means of
which he carries impressions from the outer world to the seat of
consciousness, and by which in turn he imprints his consciousness upon
the outer world.

[Sidenote: Intentional Grasping]