The unprejudiced study of experience, in perceiving and conceiving,
such as we have attempted to describe it in the preceding chapters,
is liable to be interfered with again and again by certain ideas which
spring from the soil of natural science. Thus, taking our stand on
science, we say that the eye perceives in the spectrum colours from
red to violet. But beyond violet there lie rays within the compass
of the spectrum to which corresponds, not a colour perceived by the
eye, but a chemical effect. Similarly, beyond the rays which make
us perceive red, there are rays which have only heat effects. These
and similar phenomena lead, on reflection, to the view that the range
of man's perceptual world is defined by the range of his senses, and
that he would perceive a very different world if he had additional, or
altogether different, senses. Those who like to indulge in far-roaming
fancies in this direction, for which the brilliant discoveries
of recent scientific research provide a highly tempting occasion,
may well be led to confess that nothing enters the field of man's
observation except what can affect his senses, as these have been
determined by his whole organisation. Man has no right to regard
his percepts, limited as these are by his organisation, as in any
way a standard to which reality must conform. Every new sense would
confront him with a different picture of reality. Within its proper
limits, this is a wholly justified view. But if anyone lets himself
be confused by this view in the unprejudiced study of the relation
of percept and concept, as set forth in these chapters, he blocks
the path for himself to a knowledge of man and the world which is
rooted in reality. The experience of the essential nature of thought,
i.e., the active construction of the world of concepts, is something
wholly different from the experience of a perceptible object through
the senses. Whatever additional senses man might have, not one would
give him reality, if his thinking did not organise with its concepts
whatever he perceived by means of such a sense. Every sense, whatever
its kind, provided only it is organised by thought, enables man to
live right in the real. The fancy-picture of other perceptual worlds,
made possible by other senses, has nothing to do with the problem of
how it is that man stands in the midst of reality. We must clearly
understand that every perceptual picture of the world owes its form
to the physical organisation of the percipient, but that only the
percepts which have been organised by the living labour of thought
lead us into reality. Fanciful speculations concerning the way
the world would appear to other than human souls, can give us no
occasion to want to understand man's relation to the world. Such a
desire comes only with the recognition that every percept presents
only a part of the reality it contains, and that, consequently,
it leads us away from its own proper reality. This recognition is
supplemented by the further one that thinking leads us into the part
of reality which the percept conceals in itself. Another difficulty
in the way of the unprejudiced study of the relation we have here
described, between percept and concept as elaborated by thought, may
be met with occasionally, when in the field of physics the necessity
arises of speaking, not of immediately perceptible elements, but
of non-perceptible magnitudes, such as, e.g., lines of electric or
magnetic force. It may seem as if the elements of reality of which
physicists speak, had no connection either with what is perceptible,
or with the concepts which active thinking has elaborated. Yet such
a view would depend on self-deception. The main point is that all
the results of physical research, except illegitimate hypotheses
which ought to be excluded, have been gained through perceiving and
conceiving. Entities which are seemingly non-perceptible, are referred
by the physicists' sound instinct for knowledge to the field in which
actual percepts lie, and they are dealt with in thought by means of the
concepts which are commonly applied in this field. The magnitudes in
a field of electric or magnetic force are reached, in their essence,
by no other cognitive process than the one which connects percept and
concept.--An increase or a modification of human senses would yield
a different perceptual picture, an enrichment or a modification of
human experience. But genuine knowledge could be gained out of this
new experience only through the mutual co-operation of concept and
percept. The deepening of knowledge depends on the powers of intuition
which express themselves in thinking (see page 90). Intuition may,
in those experiences in which thinking expresses itself, dive
either into deeper or shallower levels of reality. An expansion of
the perceptual picture may supply stimuli for, and thus indirectly
promote, this diving of intuition. But this diving into the depth,
through which we attain reality, ought never to be confused with the
contrast between a wider and a narrower perceptual picture, which
always contains only half of reality, as that is conditioned by the
structure of the knower's organism. Those who do not lose themselves
in abstractions will understand how for a knowledge of human nature
the fact is relevant, that physics must infer the existence, in the
field of percepts, of elements to which no sense is adapted as it is to
colour or sound. Human nature, taken concretely, is determined not only
by what, in virtue of his physical organisation, man opposes to himself
as immediate percept, but also by all else which he excludes from
this immediate percept. Just as life needs unconscious sleep alongside
of conscious waking experience, so man's experience of himself needs
over and above the sphere of his sense-perception another sphere--and
a much bigger one--of non-perceptible elements belonging to the same
field from which the percepts of the senses come. Implicitly all this
was already laid down in the original argument of this book. The
author adds the present amplification of the argument, because he
has found by experience that some readers have not read attentively
enough. It is to be remembered, too, that the idea of perception,
developed in this book, is not to be confused with the idea of external
sense-perception which is but a special case of the former. The reader
will gather from what has preceded, but even more from what will be
expounded later, that everything is here taken as "percept" which
sensuously or spiritually enters into man's experience, so long as it
has not yet been seized upon by the actively constructed concept. No
"senses," as we ordinarily understand the term, are necessary in
order to have percepts of a psychical or spiritual kind. It may be
urged that this extension of ordinary usage is illegitimate. But the
extension is absolutely indispensable, unless we are to be prevented
by the current sense of a word from enlarging our knowledge of certain
realms of facts. If we use "percept" only as meaning "sense-percept,"
we shall never advance beyond sense-percepts to a concept fit for the
purposes of knowledge. It is sometimes necessary to enlarge a concept
in order that it may get its appropriate meaning within a narrower
field. Again, it is at times necessary to add to the original content
of a concept, in order that the original thought may be justified
or, perhaps, readjusted. Thus we find it said here in this book:
"An idea is nothing but an individualised concept." It has been
objected that this is a solecism. But this terminology is necessary
if we are to find out what an idea really is. How can we expect any
progress in knowledge, if every one who finds himself compelled to
readjust concepts, is to be met by the objection: "This is a solecism"?