or while carrying on a conversation, or while
thinking about something else. As a rule, pleasure and confidence come
with skill. Playing a difficult piece on the piano involves a skill
which is one of the most complicated that man achieves. It is possible
only through habituation of the piano-playing movements.

Nailing shingles on a roof illustrates well the various aspects of
habituation. The expert carpenter not only nails on many more shingles
in a day than does the amateur, but he does it better and with more
ease, and with much less fatigue. The carpenter knows exactly how much
he can do in a day, and each particular movement is certain and sure.
The carpenter has confidence in, and usually prides himself on, this
ability, thus getting pleasure out of his work.

The operations in arithmetic illustrate most of the results of
habituation. Practice in addition makes for speed and accuracy. In a few
weeks' time we can very much increase our speed and accuracy in adding,
or in the other arithmetical operations.

The foregoing examples are sufficient, although they could be multiplied
indefinitely. Almost any habit one might name would show clearly most of
the results enumerated. The most important aspects of habituation may be
summed up in the one word _efficiency_. Habituation gives us speed and
accuracy. Speed and accuracy mean skill. Skill means efficiency.

=How Habits Are Formed.= It is clear from the foregoing discussion that
the essential thing in a habit is the definiteness of the connection
between the stimulus and the response, between the situation and the
reaction to the situation. Our question now is, how is this definiteness
of connection established? The answer is, _through repetition_. Let us
work the matter out from a concrete case, such as learning to play the
piano. In piano playing the stimulus comes from the music as printed on
the staff. A note having a certain position on the staff indicates that
a certain key is to be struck. We are told by our music teacher what
keys on the piano correspond to the various notes on the staff, or we
may learn these facts from the instruction book. It makes no difference
how we learn them; but after we know these facts, we must have practice
to give us skill. The mere knowledge will not make us piano players. In
order to be skillful, we must have much practice not only in striking
the keys indicated by the various note positions, but with the various
combinatio