two steps
you would begin to tremble, and _in spite of every effort of your
will_ you would be certain to fall to the ground.

Why is it then that you would not fall if the plank is on the ground,
and why should you fall if it is raised to a height above the ground?
Simply because in the first case you imagine that it is easy to go to
the end of this plank, while in the second case you _imagine_ that
you _cannot_ do so.

Notice that your will is powerless to make you advance; if you
_imagine_ that you _cannot_, it is _absolutely_ impossible for you
to do so. If tilers and carpenters are able to accomplish this feat, it is
because they think they can do it.

Vertigo is entirely caused by the picture we make in our minds that
we are going to fall. This picture transforms itself immediately into
fact _in spite of all the efforts of our will_, and the more violent
these efforts are, the quicker is the opposite to the desired result
brought about.

Let us now consider the case of a person suffering from insomnia. If
he does not make any effort to sleep, he will lie quietly in bed. If on
the contrary he tries to force himself to sleep by his _will_, the
more efforts he makes, the more restless he becomes.

Have you not noticed that the more you try to remember the name of
a person which you have forgotten, the more it eludes you, until,
substituting in your mind the idea "I shall remember in a minute" to
the idea "I have forgotten", the name comes back to you of its own
accord without the least effort?

Let those of you who are cyclists remember the days when you were
learning to ride. You went along clutching the handle bars and
frightened of falling. Suddenly catching sight of the smallest
obstacle in the road you tried to avoid it, and the more efforts you
made to do so, the more surely you rushed upon it.

Who has not suffered from an attack of uncontrollable laughter,
which bursts out more violently the more one tries to control it?

What was the state of mind of each person in these different
circumstances? "_I do not want_ to fall but I _cannot help_ doing
so"; "I _want_ to sleep but I _cannot_ "; "I _want_ to remember the
name of Mrs. So and So, but I _cannot_ "; "I _want_ to avoid the
obstacle, but I _cannot_ "; "I _want_ to stop laughing, but I
_cannot_."

As you see, in each of these conflicts it is always the _imagination_
which gains the victory over the _will_, without any exception.

To the same