ling in the
reverse direction, from a probable meaning to the print which you
are interpreting. This is what causes mistakes in reading, and the
well-known difficulty in seeing printing errors.

This observation is confirmed by curious experiments. Write some
everyday phrase or other on a blackboard; let there be a few intentional
mistakes here and there, a letter or two altered, or left out. Place the
words in a dark room in front of a person who, of course, does not
know what has been written. Then turn on the light without allowing the
observer sufficient time to spell the writing.

In spite of this, he will in most cases read the entire phrase, without
hesitation or difficulty.

He has restored what was missing, or corrected what was at fault.

Now, ask him what letters he is certain he saw, and you will find he
will tell you an omitted or altered letter as well as a letter actually
written.

The observer then thinks he sees in broad light a letter which is not
there, if that letter, in virtue of the general sense, ought to appear
in the phrase. But you can go further, and vary the experiment.

Suppose we write the word "tumult" correctly. After doing so, to direct
the memory of the observer into a certain trend of recollection, call
out in his ear, during the short time the light is turned on, another
word of different meaning, for example, the word "railway."

The observer will read "tunnel"; that is to say, a word, the graphical
outline of which is like that of the written word, but connected in
sense with the order of recollection called up.

In this mistake in reading, as in the spontaneous correction of the
previous experiment, we see very clearly that perception is always the
fulfilment of guesswork.

It is the direction of this work that we are concerned to determine.

According to the popular idea, perception has a completely speculative
interest: it is pure knowledge. Therein lies the fundamental mistake.

Notice first of all how much more probable it is, a priori, that the
work of perception, just as any other natural and spontaneous work,
should have a utilitarian signification.

"Life," says Mr Bergson with justice, "is the acceptance from objects of
nothing but the useful impression, with the response of the appropriate
reactions." ("Laughter", page 154.)

And this view receives striking objective confirmation if, with the
author of "Matter and Memory", we follow the progress of the perc