ature can be very much changed. To a large extent, a man is
_made_, his nature is _acquired_. After we become men and women, we have
hundreds and thousands of tendencies to action, definite forms of
action, that we did not have when young. Man's nature might be said to
consist in his tendencies to action. Some of these tendencies he
inherits; these are his instincts. Some of these he acquires; these are
his habits.

=What Habits Do for Us.= We have found out what habits are like; let us
now see what they do for us. What good do they accomplish for us? How
are we different after forming a habit from what we were before? We can
best answer these questions by a consideration of concrete cases.
Typewriting will serve very well the purpose of illustration. We shall
give the result of an actual experiment in which ten university students
took part. During their first half hour of practice, they wrote an
average of 120 words. At the end of forty-five hours of practice, they
were writing an average of 680 words in a half hour. This was an
increase of speed of 560 per cent. An expert typist can write about
3000 words in a half hour. Such a speed requires much more than
forty-five hours practice, and is attained by the best operators only.

[Illustration: FIGURE III.--LEARNING CURVES
The upper graph shows the improvement in speed of a group of students
working two half hours a day. The lower curve shows the improvement of a
group working ten half-hours a day.]

In the foregoing experiment, the students improved in accuracy also. At
the beginning of the work, they made 115 errors in the half hour. At the
end of the practice, with much faster speed, they were making only
327 errors in a half hour. The actual number of errors had increased
280 per cent. The increase in errors was therefore exactly half as much
as the increase in speed. This, of course, was a considerable increase
in accuracy, for while the speed had increased to 5.6 times what it had
been at the beginning, the errors had increased only 2.8 times. The
subjects in this experiment paid much more attention to speed than they
did to accuracy. If they had emphasized accuracy, they would have been
doing almost perfect work at the end of the practice, and their speed
would have been somewhat less. Practice, then, not only develops speed
but also develops accuracy.

There are also other results. At the beginning of work with the
typewriter, there is much waste of energy