ystem more and more appropriate paths, and
these vital phenomena recur under similar excitements from without, when
they have been interrupted for a certain time."[2]

ALL LIVING TISSUE PLASTIC.--What is true of inanimate matter is doubly
true of living tissue. The tissues of the human body can be molded into
almost any form you choose if taken in time. A child may be placed on
his feet at too early an age, and the bones of his legs form the habit
of remaining bent. The Flathead Indian binds a board on the skull of his
child, and its head forms the habit of remaining flat on the top. Wrong
bodily postures produce curvature of the spine, and pernicious modes of
dress deform the bones of the chest. The muscles may be trained into the
habit of keeping the shoulders straight or letting them droop; those of
the back, to keep the body well up on the hips, or to let it sag; those
of locomotion, to give us a light, springy step, or to allow a shuffling
carriage; those of speech, to give us a clear-cut, accurate
articulation, or a careless, halting one; and those of the face, to give
us a cheerful cast of countenance, or a glum and morose expression.

HABIT A MODIFICATION OF BRAIN TISSUE.--But the nervous tissue is the
most sensitive and easily molded of all bodily tissues. In fact, it is
probable that the real _habit_ of our characteristic walk, gesture, or
speech resides in the brain, rather than in the muscles which it
controls. So delicate is the organization of the brain structure and so
unstable its molecules, that even the perfume of the flower, which
assails the nose of a child, the song of a bird, which strikes his ear,
or the fleeting dream, which lingers but for a second in his sleep, has
so modified his brain that it will never again be as if these things had
not been experienced. Every sensory current which runs in from the
outside world; every motor current which runs out to command a muscle;
every thought that we think, has so modified the nerve structure through
which it acts, that a tendency remains for a like act to be repeated.
Our brain and nervous system is daily being molded into fixed habits of
acting by our thoughts and deeds, and thus becomes the automatic
register of all we do.

The old Chinese fairy story hits upon a fundamental and vital truth.
These celestials tell their children that each child is accompanied by
day and by night, every moment of his life, by an invisible fairy, who
is provided wit