investigation on which we are engaged.

Who was it defined art as nature seen through a mind? Perception, too, is
an art.

This art has its processes, its conventions, and its tools. Go into a
laboratory and study one of those complex instruments which make our senses
finer or more powerful; each of them is literally a sheaf of materialised
theories, and by means of it all acquired science is brought to bear on
each new observation of the student. In exactly the same way our organs of
sense are actual instruments constructed by the unconscious work of the
mind in the course of biological evolution; they too sum up and give
concrete form and expression to a system of enlightening theories. But
that is not all. The most elementary psychology shows us the amount of
thought, in the correct sense of the term, recollection, or inference,
which enters into what we should be tempted to call pure perception.

Establishment of fact is not the simple reception of the faithful imprint
of that fact; it is invariably interpreted, systematised, and placed in
pre-existing forms which constitute veritable theoretical frames. That is
why the child has to learn to perceive. There is an education of the
senses which he acquires by long training. One day, which aid of habit, he
will almost cease to see things: a few lines, a few glimpses, a few simple
signs noted in a brief passing glance, will enable him to recognise them;
and he will hardly retain any more of reality than its schemes and symbols.

"Perception," says Mr Bergson on this subject, "becomes in the end only an
opportunity of recollection." ("Matter and Memory", page 59.)

All concrete perception, it is true, is directed less upon the present than