act under the stimulus of conscious sensation,
becomes so accustomed to perform that act that it does it when the
oft-felt peripheral impulse comes again to it, although the cerebral
functions and consciousness are suspended. A nerve-centre, even of the
lowest kind, once moulded by repeated acts, retains their
impression--i.e. remembers them. Learning to walk is, as was shown in
the last paper, training the memory of the lower nerve-centres at the
base of the brain until at last they direct the movements of walking
without aid from consciousness. The musician studies a piece of music.
At first the notes are struck in obedience to a conscious act of the
will founded upon a conscious recognition of the printed type. By and by
the piece is so well known that it is played even when the attention is
directed to some other subject; that is, the act of playing has been
repeated until the lower nerve-centres, which preside over the movements
of the fingers during the playing, have been so impressed that when once
the impulses are started they flow on uninterruptedly until the whole
set has been gone through and the piece of music is finished. This is
the result of memory of the lower nerve-centres. At first, the child
reads only by a distinct conscious effort of memory, recalling painfully
each word. After a time the words become so impressed upon the lower
nerve-centres that we may read on when our attention is directed to some
other thing. Thus, often we read aloud and are unconscious of what we
have read, precisely as the compositor habitually sets up pages of
manuscript without the faintest idea of what it is all about. This law
of habitual action applies not only to the lower nerve-centres in their
healthy condition, but with equal force in disease. It is notorious that
one of the great difficulties in the cure of epilepsy is the habit which
is acquired by the nerve-centres of having at intervals attacks of
convulsive discharge of nerve-force. Some years since I saw in
consultation a case which well illustrates this point. A boy was struck
in the head with a brick, and dropped unconscious. On coming to be was
seized with an epileptic convulsion. These convulsions continually
recurred for many months before I saw him. He never went two hours
without them, and had usually from thirty to forty a day--some, it is
true, very slight, but others very severe. Medicines had no influence
over him, and with the idea that there might b