Theaetetus
succession of momentary perceptions. At this point the modern philosophy
of experience forms an alliance with ancient scepticism.
The higher truths of philosophy and religion are very far removed from
sense. Admitting that, like all other knowledge, they are derived from
experience, and that experience is ultimately resolvable into facts
which come to us through the eye and ear, still their origin is a
mere accident which has nothing to do with their true nature. They
are universal and unseen; they belong to all times--past, present, and
future. Any worthy notion of mind or reason includes them. The proof of
them is, 1st, their comprehensiveness and consistency with one another;
2ndly, their agreement with history and experience. But sensation is of
the present only, is isolated, is and is not in successive moments. It
takes the passing hour as it comes, following the lead of the eye or
ear instead of the command of reason. It is a faculty which man has in
common with the animals, and in which he is inferior to many of them.
The importance of the senses in us is that they are the apertures of the
mind, doors and windows through which we take in and make our own the
materials of knowledge. Regarded in any other point of view sensation
is of all mental acts the most trivial and superficial. Hence the term
'sensational' is rightly used to express what is shallow in thought and
feeling.
We propose in what follows, first of all, like Plato in the Theaetetus,
to analyse sensation, and secondly to trace the connexion between
theories of sensation and a sensational or Epicurean philosophy.
Paragraph I. We, as well as the ancients, speak of the five senses, and
of a sense, or common sense, which is the abstraction of them. The
term 'sense' is also used metaphorically, both in ancient and modern
philosophy, to express the operations of the mind which are immediate or
intuitive. Of the five senses, two--the sight and the hearing--are of
a more subtle and complex nature, while two others--the smell and the
taste--seem to be only more refined varieties of touch. All of them
are passive, and by this are distinguished from the active faculty of
speech: they receive impressions, but do not produce them, except in so
far as they are objects of sense themselves.
Physiology speaks to us of the wonderful apparatus of nerves, muscles,
tissues, by which the senses are enabled to fulfil their functions. It
traces the connexion, though imperfectly, of the bodily organs with the
operations of the mind. Of these latter, it seems rather to know the
conditions than the causes. It can prove to us that without the brain we
cannot think, and that without the eye we cannot see: and yet there is
far more in thinking and seeing than is given by the brain and the eye.
It observes the 'concomitant variations' of body and mind. Psychology,
on the other hand, treats of the same subject regarded from another
point of view. It speaks of the relation of the senses to one another;
it shows how they meet the mind; it analyzes the transition from sense
to thought. The one describes their nature as apparent to the outward
eye; by the other they are regarded only as the instruments of the mind.
It is in this latter point of view that we propose to consider them.
The simplest sensation involves an unconscious or nascent operation
of the mind; it implies objects of sense, and objects of sense have
differences of form, number, colour. But the conception of an object
without us, or the power of discriminating numbers, forms, colours,
is not given by the sense, but by the mind. A mere sensation does not
attain to distinctness: it is a confused impression, sugkechumenon ti,
as Plato says (Republic), until number introduces light and order
into the confusion. At what point confusion becomes distinctness is a
question of degree which cannot be precisely determined. The distant
object, the undefined notion, come out into relief as we approach
them or attend to them. Or we may assist the analysis by attempting
to imagine the world first dawning upon the eye of the infant or of a
person newly restored to sight. Yet even with them the mind as well
as the eye opens or enlarges. For all three are inseparably bound
together--the object would be nowhere and nothing, if not perceived by
the sense, and the sense would have no power of distinguishing without
the mind.
But prior to objects of sense there is a third nature in which they
are contained--that is to say, space, which may be explained in various
ways. It is the element which surrounds them; it is the vacuum or void
which they leave or occupy when passing from one portion of space to
another. It might be described in the language of ancient philosophy, as
'the Not-being' of objects. It is a negative idea which in the course
of ages has become positive. It is originally derived from the
contemplation of the world without us--the boundless earth or sea, the
vacant heaven, and is therefore acquired chiefly through the sense of
sight: to the blind the conception of space is feeble and inadequate,
derived for the most part from touch or from the descriptions of others.
At first it appears to be continuous; afterwards we perceive it to be
capable of division by lines or points, real or imaginary. By the
help of mathematics we form another idea of space, which is altogether
independent of experience. Geometry teaches us that the innumerable
lines and figures by which space is or may be intersected are absolutely
true in all their combinations and consequences. New and unchangeable
properties of space are thus developed, which are proved to us in a
thousand ways by mathematical reasoning as well as by common experience.
Through quantity and measure we are conducted to our simplest and purest
notion of matter, which is to the cube or solid what space is to
the square or surface. And all our applications of mathematics are
applications of our ideas of space to matter. No wonder then that they
seem to have a necessary existence to us. Being the simplest of our
ideas, space is also the one of which we have the most difficulty in
ridding ourselves. Neither can we set a limit to it, for wherever we
fix a limit, space is springing up beyond. Neither can we conceive a
smallest or indivisible portion of it; for within the smallest there
is a smaller still; and even these inconceivable qualities of space,
whether the infinite or the infinitesimal, may be made the subject of
reasoning and have a certain truth to us.
Whether space exists in the mind or out of it, is a question which has
no meaning. We should rather say that without it the mind is incapable
of conceiving the body, and therefore of conceiving itself. The mind may
be indeed imagined to contain the body, in the same way that Aristotle
(partly following Plato) supposes God to be the outer heaven or circle
of the universe. But how can the individual mind carry about the
universe of space packed up within, or how can separate minds have
either a universe of their own or a common universe? In such conceptions
there seems to be a confusion of the individual and the universal. To
say that we can only have a true idea of ourselves when we deny the
reality of that by which we have any idea of ourselves is an absurdity.
The earth which is our habitation and 'the starry heaven above' and
we ourselves are equally an illusion, if space is only a quality or
condition of our minds.
Again, we may compare the truths of space with other truths derived from
experience, which seem to have a necessity to us in proportion to the
frequency of their recurrence or the truth of the consequences which may
be inferred from them. We are thus led to remark that the necessity
in our ideas of space on which much stress has been laid, differs in a
slight degree only from the necessity which appears to belong to other
of our ideas, e.g. weight, motion, and the like. And there is another
way in which this necessity may be explained. We have been taught it,
and the truth which we were taught or which we inherited has never been
contradicted in all our experience and is therefore confirmed by it. Who
can resist an idea which is presented to him in a general form in every
moment of his life and of which he finds no instance to the contrary?
The greater part of what is sometimes regarded as the a priori intuition
of space is really the conception of the various geometrical figures of
which the properties have been revealed by mathematical analysis. And
the certainty of these properties is immeasurably increased to us by our
finding that they hold good not only in every instance, but in all the
consequences which are supposed to flow from them.
Neither must we forget that our idea of space, like our other ideas,
has a history. The Homeric poems contain no word for it; even the later
Greek philosophy has not the Kantian notion of space, but only the
definite 'place' or 'the infinite.' To Plato, in the Timaeus, it is
known only as the 'nurse of generation.' When therefore we speak of
the necessity of our ideas of space we must remember that this is a
necessity which has grown up with the growth of the human mind, and
has been made by ourselves. We can free ourselves from the perplexities
which are involved in it by ascending to a time in which they did not
as yet exist. And when space or time are described as 'a priori forms or
intuitions added to the matter given in sensation,' we should consider
that such expressions belong really to the 'pre-historic study' of
philosophy, i.e. to the eighteenth century, when men sought to explain
the human mind without regard to history or language or the social
nature of man.
In every act of sense there is a latent perception of space, of which
we only become conscious when objects are withdrawn from it. There are
various ways in which we may trace the connexion between them. We may
think of space as unresisting matter, and of matter as divided into
objects; or of objects again as formed by abstraction into a collective
notion of matter, and of matter as rarefied into space. And motion may
be conceived as the union of there and not there in space, and force
as the materializing or solidification of motion. Space again is the
individual and universal in one; or, in other words, a perception and
also a conception. So easily do what are sometimes called our simple
ideas pass into one another, and differences of kind resolve themselves
into differences of degree.
Within or behind space there is another abstraction in many respects
similar to it--time, the form of the inward, as space is the form of the
outward. As we cannot think of outward objects of sense or of outward
sensations without space, so neither can we think of a succession of
sensations without time. It is the vacancy of thoughts or sensations,
as space is the void of outward objects, and we can no more imagine
the mind without the one than the world without the other. It is to
arithmetic what space is to geometry; or, more strictly, arithmetic may
be said to be equally applicable to both. It is defined in our minds,
partly by the analogy of space and partly by the recollection of events
which have happened to us, or the consciousness of feelings which we are
experiencing. Like space, it is without limit, for whatever beginning or
end of time we fix, there is a beginning and end before them, and so
on without end. We speak of a past, present, and future, and again the
analogy of space assists us in conceiving of them as coexistent. When
the limit of time is removed there arises in our minds the idea of
eternity, which at first, like time itself, is only negative, but
gradually, when connected with the world and the divine nature, like