Chapter 4 The World As Percept

    Chapter 4 The World
        as Percept

 
    [1] Through thinking,
       concepts
           and ideas arise.

    What
         a concept
            is
        cannot be expressed
           in words.

    Words
        can do
           no more than draw
              our attention
                 to the fact
         that we
              have concepts.

    When someone
          sees a tree,
       his thinking
          reacts to
             his observation,
       an ideal element
          is added
             to the object,
       and
          he considers
             the object
                and the ideal complement
           as belonging together.

    When
         the object disappears
            from his field
               of observation,
       only the ideal counterpart
           of it remains.

    This latter
        is the concept
           of the object.

    The more
         our range
            of experience
               is widened,
       the greater
          becomes
             the sum
           of our concepts.

    But
         concepts
              certainly do not stand
            isolated
           from one another.

    They combine
          to form
             a systematically ordered whole.

    The concept "organism",
       for instance,
          links up
             with those
           of "orderly development"
               and "growth".

    Other concepts
          which
              are based on single objects
           merge together into a unity.

    All concepts
          I may form of lions
             merge
            into the collective concept "lion".

    In this
         way all the separate
            concepts
               combine to form
                  a closed conceptual system
         in which
            each has its special place.

    Ideas
         do not differ qualitatively
            from concepts.

    They are
         but fuller,
            more saturated,
               more comprehensive concepts.

    I must attach
        special importance
           to the necessity
              of bearing
                 in mind,
                here,
                   that I
                      make thinking my starting point,
      and
         not concepts
            and ideas
        which
           are first gained
          by means of thinking.

    For
         these latter already presuppose thinking.

    My remarks
        regarding
           the self-supporting and self-determined nature
              of thinking cannot,
           therefore,
              be simply transferred
                 to concepts.

    (I make special
        mention of this,
       because it
          is here
             that
                 I differ
               from Hegel,
       who regards
           the concept
              as something primary and original.)
 
    [2] Concepts
        cannot be gained
           through observation.

    This follows
        from the simple fact
       that the growing human being
         only slowly
            and gradually forms
               the concepts corresponding
        to the objects
           which surround him.

    Concepts
        are added
           to observation.
 
    [3] A philosopher widely read
        at the present day
       -- Herbert Spencer, --
             describes
                   the mental process
                 which
                     we carry out
                   with respect
                      to observation
                 as follows:

    [4] If,
       when walking
           through the fields some day
               in September,
       you hear
           a rustle
              a few yards
                 in advance,
       and
          on observing
             the ditch-side
         where
             it occurs,
       see
          the herbage agitated,
       you will probably turn towards
          the spot to learn
             by what
                this sound
                   and motion are produced.

    As you
          approach
             there
            flutters
           into the ditch a partridge;
       on seeing
          which
             your curiosity
                is satisfied
       -- you have
          what
         you call an explanation
            of the appearances.

    The explanation,
       mark,
          amounts to this;
             that whereas
                throughout life
                   you
                have had
                    countless experiences of disturbance
                   among small stationary bodies,
       accompanying the movement
           of other bodies
               among them,
       and have generalized
           the relation
              between such disturbances
                 and such movements,
       you consider
          this particular disturbance explained
             on finding
                it
              to present
                  an instance
                     of the like relation.

    A closer analysis
        shows
           matters
          to stand very differently
             from the way described above.

    When
         I hear a noise,
       I first look
          for the concept
             which fits this observation.

    It is this concept
          which
             first leads me
           beyond the mere noise.

    If one
          thinks no further,
       one simply hears
           the noise
        and is content
           to leave
              it
           at that.

    But my reflecting
        makes
           it clear
              to me
             that
                 I have
                    to regard
                       the noise
                   as an effect.

    Therefore not until
         I have connected
            the concept
           of effect
              with the perception
                 of the noise,
       do I
          feel the need to go
             beyond the solitary observation
                and
            look
               for the cause.

    The concept
        of effect
           calls up that of cause,
      and my next step.
         is to look
            for the object
               which is being the cause,
      which
         I find
            in the shape
               of the partridge.

    But these concepts,
       cause and effect,
          I can never gain through
             mere observation,
       however many instances the observation
          may cover.

    Observation
        evokes thinking,
       and
          it is thinking that
        first shows me how
           to link
              one separate experience
           to another.
 
    [5] If one
        demands
           of a
        "strictly
           objective science"
              that it should take
                 its content
               from observation alone,
           then
              one must
                 at the same time
            demand
               that it
                  should forego all thinking.

    For thinking,
       by its very nature,
          goes
             beyond what
            is observed.
 
    [6] We must now pass
        from thinking
           to the being
          that thinks;
      for it
         is
            through the thinker
               that thinking
           is combined
              with observation.

    Human consciousness
        is the stage
           upon which concept
               and observation
            meet
                  and become
                linked
               to one another.

    In saying
          this
             we have in fact characterized
                this (human) consciousness.

    It is the mediator
        between thinking
            and observation.

    In as far as we
        observe
           a thing it appears
              to us as given;
       in as far as we think,
          we appear
             to ourselves
         as being active.

    We regard
        the thing
       as object
         and ourselves
        as thinking subject.

    Because
         we direct our thinking
            upon our observation,
       we have consciousness of objects;
          because
         we direct it upon ourselves,
       we have consciousness of ourselves,
          or self-consciousness.

    Human consciousness
        must
           of necessity
              be
           at the same time
               self-consciousness
          because it
              is a consciousness
         which thinks.

    For when
        thinking contemplates
            its own activity,
      it makes
          its own essential being,
             as subject,
          into a thing,
      as object.
 
    [7] It must,
       however,
          not be overlooked
             that
         only with the help
            of thinking
               am
         I able
            to determine myself
           as subject and
               contrast myself with objects.

    Therefore thinking
        must never be regarded
           as a merely subjective activity.

    Thinking
        lies
           beyond subject
              and object.

    It produces
        these two concepts
       just
      as it produces
         all others.

    When,
       therefore,
          I,
       as thinking subject,
          refer a concept
             to an object,
       we must not regard
           this reference
              as something
                 purely subjective.

    It is not the subject
          that makes the reference,
       but thinking.

    The subject
        does not think
           because it is a subject;
       rather it
          appears
             to itself
         as subject
             because it can think.

    The activity
        exercised
           by man
              as a thinking being is thus
          not merely subjective.

    Rather is it something
        neither subjective
           nor objective,
      that transcends both these concepts.

    I ought never
          to say
         that my individual subject
            thinks,
       but much more
           that my individual subject lives
              by the grace
                 of thinking.

    Thinking is thus
        an element
       which
         leads
        me out
           beyond myself and
         connects me
            with the objects.

    But
         at the same time
            it separates me from them,
       inasmuch as
          it sets me,
             as subject,
           over against them.
 
    [8] It is just
          this
             which constitutes
                the double nature
                   of the human being.

    We think,
       and thereby embrace
           both ourselves and the rest
              of the world.

    But
         at the same time
             it is
           by means
               of thinking
              that
                 we determines ourselves
                    as an individual confronting
          the things.
 
    [9] We must next
          ask ourselves how
             that other element,
       which we
          have so far simply called
             the object
           of observation
               and
                  which meets
                     the thinking
                   in our consciousness,
       comes
          into our consciousness
             at all.
 
    [10] In order to
          answer
             this question
                we must eliminate
               from our field
                   of observation
             everything
                 that has been imported
           by thinking.

    For
         at any moment
             the content
                of our consciousness
                   will already be interwoven
           with concepts
               in the most varied ways.
 
    [11] We must imagine
          that
             a being
                with fully developed
                   human intelligence
                      originates
           out of nothing
              and confronts
                 the world.

    What
         it would be aware
            of,
       before it
          sets
         its thinking
            in motion,
       would be
          the pure content
             of observation.

    The world
        would
           then appear
              to this
            being
               as nothing
              but
                 a mere disconnected aggregate
               of objects
                  of sensation:
       colors,
          sounds,
       sensations
           of pressure,
       of warmth,
          of taste
             and smell;
       also feelings
           of pleasure and pain.

    This aggregate
        is the content
           of pure,
       unthinking observation.

    Over against it
        stands thinking,
       ready
          to begin
             its activity
           as soon
              as a point
                 of attack
                presents itself.

    Experience
        shows
           at once
          that this does happen.

    Thinking is able
          to draw
              threads
           from one element
               of observation
                   to another.

    It links definite concepts
        with these elements
           and thereby establishes
       a relationship
          between them.

    We have already seen how
        a noise
       which
          we hear
             becomes
                 connected
        with another observation
           by our identifying the former
        as the effect
            of the latter.

    [12] If now
         we recollect
             that the activity
                of thinking
                   is
               on no account
              to be considered
                 as merely subjective,
       then we
          shall also not be tempted
              to believe
                 that
           the relationships
              thus established
           by thinking
          have merely subjective validity.
 
    [13] Our next task
        is to discover
           by means
              of thoughtful reflection
         what relation
            the immediately given content
           of observation
              mentioned
            above has
               to the conscious subject.
 
    [14] The ambiguity of current speech
        makes it necessary
           for me to come
              to an agreement
                 with my readers
          concerning the use
             of a word
         which
             I shall have
          to employ
             in what follows.

    I shall apply
          the word "percept"
             to the immediate objects
                of sensation
                   enumerated above,
       in so far
           as the conscious subject
              apprehends them
                 through observation.

    It is,
       then,
          not the process
             of observation
         but the object
            of observation
               which I
              call the "percept".
 
    [15] I do not choose
        the term "sensation",
       since this
          has a definite meaning
             in physiology
         which is narrower
            than
         that
            of my concept
           of "percept".

    I can speak
        of a feeling
           in myself (emotion)
              as percept,
      but not
          as sensation
              in the physiological sense
                  of the term.

    Even my feeling
        becomes
            known
           to me
               by becoming
                   a percept
                       for me.

    And the way
         in which
            we
               gain
                  knowledge
                     of our thinking
                   through observation
                      is
             such that
                thinking too,
       in its first appearance
           for our consciousness,
       may be called
          a percept.
 
    [16] The naïve man
        regards
           his percepts,
       such as
          they appear
             to his immediate apprehension,
       as things
          having an existence wholly independent
             of him.

    When
         he sees
             a tree
                 he believes
                    in the first instance
         that it stands
            in the form
         which
             he sees,
       with the colors
           of its various parts,
              and so on,
           there on the spot towards which
              his gaze
            is directed.

    When the same man
          sees
              the sun
                 in the morning
                    appear
           as a disc
               on the horizon,
       and follows
          the course
             of this disc,
       he believes
          that all this
             actually exists and happens just
           as he
              observes it.

    To this belief
          he clings until
             he meets with further percepts
         which
              contradict
           his former ones.

    The child
         who
             as yet has
                no experience
               of distance
                  grasps
                     at the moon,
       and only corrects
          its picture
             of the reality,
       based
          on first impressions,
       when a second percept
          contradicts the first.

    Every extension
        of the circle
            of my percepts
       compels me
          to correct
             my picture
                of the world.

    We see this
        in everyday life,
       as well as in
           the spiritual development
              of mankind.

    The picture
         which
             the ancients
                made
           for themselves
               of the relation
                   of the earth
                       to the sun
                           and other heavenly
                      bodies had to be replaced
                         by another
         when Copernicus
            found that it
               was not
                  in accordance
                     with some percepts,
       which
          in those early days
             were unknown.

    A man
         who had been born blind said,
       when operated on
           by Dr. Franz,
       that the picture
           of the size
               of objects
         which he
            had formed
           by his sense
               of touch
                   before his operation,
       was
          a very different one.

    He had
          to correct
              his tactual percepts
           by his visual percepts.
 
    [17] How is it
         that we
            are compelled
          to make
             these continual corrections
                to our observations?
 
    [18] A simple reflection
        gives the answer
           to this question.

    When
         I stand
            at one end
               of an avenue,
       the trees
           at the other end,
              away from me,
           seem smaller and nearer
              together than
                 those
         where I stand.

    My percept-picture changes
         when
             I change
                the place
           from
              which I am looking.

    Therefore the form
         in which
            it
               presents itself
                  to me
                is dependent
           on a condition
              which is due
                 not to the object
                    but to me,
       the perceiver.

    It is all the same
        to the avenue
       wherever I stand.

    But
         the picture
             I have of it
                depends essentially
           on just this viewpoint.

    In the same way,
       it makes
           no difference
              to the sun
                 and the planetary system
                that human beings
                   happen
                  to look
                     at them
                        from the earth;
       but
          the percept-picture
             of the heavens
            presented
           to them
              is determined
           by the fact
              that they
          inhabit the earth.

    This dependence
        of our percept-picture
            on our place
                of observation
       is the easiest one
           to understand.

    The matter
        becomes more difficult
           when
              we realize how
             our world of percepts
                is dependent
               on our bodily
                  and spiritual organization.

    The physicist
        shows us
           that
         within the space
            in which
          we
              hear
                  a sound there are vibrations
                     of the air,
       and also
          that the body
         in which
             we seek
                 the origin of the sound
                    exhibits
                       a vibrating movement
                   of its parts.

    We perceive
        this movement
       as sound only
          if we
             have a normally constructed ear.

    Without this
          the world
              would be
                 for ever silent
               for us.

    Physiology
        tells us
           that there are
              people
                 who perceive
                    nothing
                       of the magnificent splendor
                          of color
         which surrounds us.

    Their percept-picture
        has only degrees
           of light and dark.

    Others are blind only
        to one color,
           for example,
        red.

    Their world picture
        lacks
           this hue,
       and
          hence
             it is actually
                 a different one
           from
         that
            of the average man.

    I should like
          to call
              the dependence
           of my percept-picture
              on my place
                 of observation,
        "mathematical",
           and its dependence
               on my organization,
           "qualitative".

    The former
        determines the proportions
           of size
               and mutual distances
                   of my percepts,
       the latter their quality.

    The fact
          that
             I see a red surface
                as red
       -- this qualitative determination --
             depends
                   on the organization
                       of my eye.

    [19] My percept-pictures,
       then,
          are
             in the first instance subjective.

    The recognition
        of the subjective character
            of our percepts
       may easily lead us
          to doubt
        whether
           there is
          any objective basis
             for them at all.

    When we
          realize that a percept,
       for example
          that
         of a red color
            or of a certain tone,
       is not possible
           without a specific structure
               of our organism,
       we may easily be led
          to believe
         that it
            has no permanency
           apart from our subjective organization
               and that,
       were it
           not for our act
               of perceiving
              it as an object,
       it would not exist
           in any sense.

    The classical representative
        of this view
           is George Berkeley,
       who held
          that
         from the moment
            we realize the importance of
               the subject
           for perception,
       we are
           no longer able
          to believe
             in the existence
                of a world
                   without a conscious Spirit:
 
    "Some truths
        there are so
           near and obvious
              to the mind
         that man
              need
          only open
             his eyes
                to see them.

    Such
         I take this
            important one
          to be,
             to wit,
                that all the choir
                   of heaven
               and furniture
                  of the earth,
           in a word,
              all those bodies
         which
              compose the mighty frame
                 of the world,
           have not any subsistence
              without a mind,
       that their being
          is to be perceived
             or known;
       that,
          consequently,
       so long
          as they
              are not actually perceived
                 by me,
       or do not exist
           in my mind
               or that
           of any other created spirit,
       they must either
          have no existence
         at all,
       or else
          subsist
             in the mind
           of some Eternal Spirit."
 
    On this view,
       when
          we take away
             the fact
           of its
              being perceived,
       nothing
          remains
             of the percept.

    There is
          no color
         when none
            is seen,
       no sound
          when none
             is heard.

    Extension,
       form,
          and
         motion
              exist
           as little
              as color
                 and sound apart
           from the act
               of perception.

    Nowhere do
         we see
              bare extension
           or shape,
       but these
          are always bound up
             with color
                or some other quality
                   unquestionably dependent
           upon our subjectivity.

    If these latter
          disappear
         when we
            cease to perceive them,
           then the former,
              being bound up
                 with them,
       must disappear likewise.
 
    [20] To the objection
         that there must be
             things that exist apart
           from consciousness
               and
         to which
             the conscious percept-pictures
                are similar,
                   even though figure,
                      color,
                   sound,
                      and so on,
                   have no existence
         except
            within the act
               of perceiving,
                   the above view
        would answer
           that a color
              can be similar
           only to a color,
       a figure
           only to a figure.

    Our percepts
        can be similar
           only to our percepts
               and to nothing else.

    Even
         what
            we call
          an object is nothing
             but a collection of percepts
                which
                   are connected
               in a particular way.

    If
         I strip a table
            of its shape,
           extension,
              color,.etc.

    -- in short,
       of all that is
           merely my percept
       -- then nothing
          remains over.

    This view,
       followed
           up logically,
       leads
          to the assertion
             that
          the objects of my perceptions
              exist only through me,
       and indeed
           only in
              as far as,
       and as long as,
          I perceive them;
             they disappear
                with my perceiving
                   and have
              no meaning apart
                 from it.

    Apart from my percepts,
       I know of no
          objects and cannot know
             of any.
 
    [21] No objection
        can be made
           to this assertion
              as long
                 as I am merely referring
                    to the general fact
                  that the percept
                      is partly determined
                         by the organization
                            of myself
                               as subject.

    The matter
        would appear very different
           if we
              were
                 in a position
              to say just
         what part
            is played
           by our perceiving
              in the bringing forth
           of a percept.

    We should
         then know
            what happens
           to a percept
              while it
                 is being perceived,
       and
          we should also be able
             to determine
         what character it
            must already possess before it
               comes
              to be perceived.
 
    [22] This
        leads us
           to turn
              our attention
           from the object
               of perception
                   to the subject
                       of perception.

    I perceive not only
        other things,
       but also myself.

    The percept of myself
        contains,
           to begin with,
              the fact that
         I am
             the stable element
           in contrast
              to the continual coming
                 and
            going
               of the percept-pictures.

    The percept
        of my "I"
           can always come up
        in my consciousness
       while
          I am having other percepts.

    When
         I am absorbed
            in the perception
               of a given
        object
           I am
              for the time
            being aware
           only of this object.

    To this
         the percept
            of my self
               can be added.

    I am
         then conscious
            not
               only of the object
                   but also of my own
             personality
                which
                   confronts
               the object
                  and observes
              it.

    I do not
        merely see a tree,
       but
          I also know
         that it
            is
         I who am seeing it.

    I know,
       moreover,
          that something
        happens
           in me
              while
                 I am observing the tree.

    When
         the tree disappears
            from my field
               of vision,
       an after-effect
           of this process
              remains
                 in my consciousness
       -- a picture
           of the tree.

    This picture
        has become
            associated
           with my self
              during my observation.

    My self
        has become enriched;
           its content
              has absorbed
          a new element.

    This element
          I call my mental picture
             of the tree.

    I should never have
          occasion
             to speak
           of mental pictures
              did
             I not experience them
           in the percept
               of my own self.

    Percepts
        would come
           and go;
              I should let them
          slip by.

    Only
         because
             I perceive
                my self,
       and observe
          that
         with each percept
            the content
               of my self, too,
                  is changed,
               am
         I compelled
            to connect
               the observation
                  of the object
               with the changes
                   in my own condition,
       and
          to speak
             of my mental picture.
 
    [23] I perceive
          the mental picture
             in my self
           in the same sense
               as I perceive color,
                  sound, etc.,
               in other objects.

    I am now also able
        to distinguish
           these other objects
              that confront me,
      by calling them
         the outer world,
      whereas
         the content
            of my percept
               of my self
            I
         call my inner world.

    The failure
          to recognize
             the true relationship
           between mental picture
              and object
            has led
               to the greatest misunderstandings
                   in modern philosophy.

    The perception
        of a change
            in me,
      the modification my self
         undergoes,
      has been
         thrust
            into the foreground,
      while
         the object
            which
               causes
                  this modification is lost sight
          of altogether.

    It has been said
          that
             we perceive
                not objects
         but
            only our mental pictures.

    I know,
       so
          it is said,
       nothing
           of the table
               in itself,
       which is the object
           of my observation,
       but
          only of the change
             which
            occurs
           within me
          while
             I am perceiving the table.

    This view
        should not be confused
           with the Berkeleyan theory
              mentioned above.

    Berkeley
        maintains
           the subjective nature
              of the content
                 of my percepts,
       but he
          does not say
             that my knowledge
                is limited
               to my mental pictures.

    He limits
        my knowledge
           to my mental pictures
      because,
         in his opinion,
        there are
       no
       objects apart
          from mental picturing.

    What
         I take to be
            a table no longer
               exists,
                  according to Berkeley,
       when
          I cease
             to look at it.

    This is

    "The first fundamental proposition
         which
            the philosopher
          must bring to clear
             consciousness
                is the recognition
         that our knowledge,
            to begin with,
           is limited
              to our mental pictures.

    Our mental pictures
        are
           the only things that
              we know directly,
       experience directly;
          and
         just
             because we
                have direct experience of them,
       even
          the most radical doubt
             cannot rob us
           of our knowledge
               of them.

    On the other hand,
       the knowledge
          which
             goes
           beyond my mental pictures
       -- taking mental
          pictures here
             in the widest possible sense,
           so
               as to include all
                   psychical processes --
             is not proof
                   against doubt.

    Hence,
       at the very
          beginning
             of all philosophizing
          we must explicitly set
             down all
                knowledge
              which goes beyond mental pictures
         as being
              open
           to doubt."
 
    These are
          the opening sentences
             of Volkelt's
                book
           on Immanuel Kant's
               Theory
                   of Knowledge.

    What is
          here
              put forward
           as an immediate
              and self-evident truth
            is
           in reality
              the result
                 of a thought operation
         which
            runs
         as follows:
       The naïve man
          believes
             that things,
       just
          as we perceive them,
       exist also outside
           our consciousness.

    Physics,
       physiology,
          and psychology,
       however,
          seem to teach us
         that
            for our percepts
         our organization
            is necessary,
       and that
          therefore
             we cannot know
                anything about external
         objects
            except
               what our organization
              transmits to us.

    Our percepts
        are thus modifications
           of our organization,
       not things-in-themselves.

    This train of thought
          has in fact been characterized
             by Eduard von
                Hartmann
               as the one
          which
             must lead
           to the conviction
              that
                 we can have
                    direct knowledge
               only of our mental pictures.

    Because,
       outside our organism,
          we find vibrations
             of physical bodies
           and of the air
         which
            are perceived
           by us as sound,
       it is concluded
          that
         what
             we call sound
                is nothing
             more than
                a subjective reaction
               of our organism
                   to these motions
                       in the external world.

    Similarly,
       it is concluded
           that color
              and
         warmth are merely modifications
            of our organism.

    And,
       further,
          these two kinds of percepts
        are held
           to be produced
              in us
            through processes
           in the external world
         which are utterly different
            from what
          we experience
             as warmth or as color.

    When
         these processes
        stimulate the nerves
           in my skin,
       I have the subjective percept
           of warmth;
       when they
          stimulate the optic nerve,
       I perceive
          light and color.

    Light,
       color,
          and warmth,
       then,
          are the responses
             of my sensory nerves
                to external stimuli.

    Even the sense
        of touch
       reveals to me,
      not the objects
          of the outer world,
      but only states
          of my own body.

    In the sense
        of modern physics
           one could somehow think
       that bodies
           consist
              of infinitely small particles
      called molecules,
      and that these molecules
         are not in direct contact,
      but are
          at certain distances
              from one another.

    Between them,
       therefore,
          is empty space.

    Across this space
         they act
            on one another
               by forces
                  of attraction
                     and repulsion.

    If
         I put
            my hand
           on a body,
       the molecules
           of my hand
               by no
                  means
          touch those
             of the body directly,
       but there remains
           a certain distance
              between body
                 and hand,
       and
          what
         I experience
            as the body's resistance
               is nothing
             but the effect
                of the force
                   of repulsion
                 which its molecules
                    exert on my hand.

    I am absolutely external
        to the body and
           perceive only its effects
              on my organism.
 
    [24] In amplification
        of this discussion,
       there is
          the theory
             of the so-called Specific Nerve Energies,
       advanced
           by J. Müller (1801-1858).

    It asserts
          that each sense
             has
                the peculiarity that it responds
           to all external stimuli
              in one particular way only.

    If
         the optic nerve
            is stimulated,
       perception
           of light results,
       irrespective
           of whether
          the stimulation
              is due to what
         we call light,
       or
          whether mechanical
              pressure
                 or an electric current works
                    upon the nerve.

    On the other hand,
       the same external stimulus
          applied
             to different senses
            gives
               rise
                  to different percepts.

    The conclusion from these facts
        seems
           to be
              that our senses
                 can transmit only
         what occurs
            in themselves,
       but nothing
           of the external world.

    They
         determine our percepts,
       each
          according to
             its own nature.
 
    [25] Physiology
        shows
           that there can be
              no direct knowledge
                 even of the effects
                    which objects produce
           on our sense organs.

    Through following
        up the processes
       which
           occur
        in our own bodies,
       the physiologist
          finds that,
       even in the sense organs,
          the effects
             of the external movement
          are transformed
             in the most manifold ways.

    We can see
          this most clearly
             in the case
                of eye and ear.

    Both are very
        complicated organs
           which
         modify the external stimulus considerably
            before they
               conduct it
                  to the corresponding nerve.

    From the peripheral end
        of the nerve
           the already modified stimulus
              is
      then conducted
         to the brain.

    Only now can
          the central organs
              be stimulated.

    Therefore it
        is concluded
           that the external process
              undergoes
                  a series
                     of transformations
                        before it
                           reaches
          consciousness.

    What goes on
        in the brain
           is connected
        by so many intermediate links
            with the external process,
      that
         any similarity to the latter
            is out of the question.

    What
         the brain
            ultimately transmits
           to the soul
              is
                  neither external
                     processes,
       nor processes
           in the sense organs,
       but
          only such as
             occur
                in the brain.

    But
         even these
            are not perceived directly
               by the soul.

    What we
        finally have in consciousness
           are not
       brain processes at all,
      but sensations.

    My sensation
        of red
           has absolutely
      no similarity
         to the process
      which
         occurs
        in the brain
       when
          I sense red.

    The redness,
       again,
          only appears
             as an effect
                in the soul,
       and
          the brain
              process
            is merely
          its cause.

    This is
         why
             Hartmann says,
        "What the subject perceives,
           therefore,
              are always only modifications
                 of his own
                    psychical states
                   and nothing else."

    When I
          have the sensations,
             however,
           they are
              as yet very far
                 from being grouped
               into what
                  I
           perceive as "things".

    Only single sensations
        can be transmitted
           to me
               by the brain.

    The sensations
        of hardness
            and softness
           are transmitted
              to me
                 by the sense
                    of touch,
      those
         of color
             and light
          by the sense
              of sight.

    Yet all
         these are
            to be found
               united
           in one
               and the same object.

    This unification,
       therefore,
          can only be brought about
             by the soul
                itself;
           that is,
       the soul
          combines
             the separate sensations,
       mediated
           through the brain,
       into bodies.

    My brain
        conveys
           to me singly,
       and
          by widely different paths,
             the visual,
           tactile,
       and auditory sensations
          which the soul
         then combines
            into the mental picture
               of a trumpet.

    It is just
          this very last link
             in a process
        (the mental picture
           of the trumpet)
              which
                 for my consciousness
                is
              the very first thing
                 that is given.

    In it nothing
          can any longer
        be found of what

    [26] It would be hard
          to find
             in the history
                of human culture
                   another
                 edifice of thought
                    which
                       has been built up
                   with greater ingenuity,
                      and which yet,
                   on closer analysis,
       collapses
           into nothing.

    Let us
          look
             a little closer
           at the way it
              has been constructed.

    One starts with what
          is given in naïve consciousness,
       with the thing
           as perceived.

    Then one shows
         that none of the qualities
             which
                 we find
               in this thing
                  would exist
                     for us
                    had
             we no sense organs.

    No eye
       -- no color.

    Therefore
         the color is not yet
        present
           in that
          which affects the eye.

    It arises first through
        the interaction
           of the eye
              and the object.

    The latter is,
       therefore,
          colorless.

    But
         neither is the color
            in the eye,
       for
          in the eye
             there is only
          a chemical or physical process
              which
                 is first conducted
               by the optic nerve
                   to the brain,
       and there initiates
          another process.

    Even
         this is not yet
            the color.

    That is only produced
        in the soul
            by means
               of the brain process.

    Even then it
         does not yet enter
            my consciousness,
       but is first transferred
           by the soul
               to a body
                   in the external world.

    There,
       upon this body,
          I finally believe myself
             to perceive it.

    We have traveled
        in a complete circle.

    We became conscious
        of a colored body.

    That is
          the first thing.

    Here the thought operation starts.

    If I
          had no eye,
       the body
          would be,
             for me,
           colorless.

    I cannot therefore attribute
        the color
           to the body.

    I start
        on the search
            for it.

    I look for it
        in the eye
       -- in vain;
           in the nerve
              -- in vain;
           in the brain
              -- in vain once more;
           in the soul
       -- here
          I find it indeed,
             but not attached
                to the body.

    I find
        the colored body again
           only on
              returning
                 to my starting point.

    The circle
        is completed.

    I believe that
         I am cognizing
            as a product
               of my soul
         that
             which the naïve man
                regards
                   as existing outside him,
       in space.
 
    [27] As long
        as one stops here
           everything
         seems
            to fit beautifully.

    But
         we must go over
            the whole thing
           again from the beginning.

    Hitherto
         I
            have been dealing with something
       -- the external percept --
             of which,
                from my naïve standpoint,
       I have had until now
          a totally wrong conception.

    I thought that
        the percept,
       just
          as I perceive it,
       had
          objective existence.

    But
         now
             I observe
                that it disappears together
               with my mental picture,
       that it
          is only a modification
             of my inner state
           of soul.

    Have I,
       then,
          any right
             at all
          to start from it
             in my arguments?

    Can
         I say of it
            that it acts
           on my soul?

    I must henceforth treat
          the table,
       of which formerly
          I believed
             that it acted
           on me
              and produced
                 a mental picture
               of itself
                  in me,
       as itself
           a mental picture.

    But
         from this
            it follows logically that
         my sense organs
            and the processes
           in them
              are also merely subjective.

    I have
          no right
             to speak
           of a real eye
               but only of my mental picture
                  of the eye.

    Exactly
         the same is true
            of the nerve paths,
       and
          the brain process,
       and no less
           of the process
               in the soul
                   itself,
       through which
          things
        are supposed
           to be built up
              out of the chaos
                 of manifold sensations.

    If,
       assuming the truth
           of the first circle
              of argumentation,
       I run
           through the steps
               of my act
                   of cognition once more,
       the latter
          reveals itself
             as a tissue
                of mental pictures
         which,
            as such,
           cannot act
              on one another.

    I cannot say
          that my mental picture
             of the object
            acts
           on my mental picture
               of the eye,
       and
          that
         from this interaction my mental
            picture
           of color results.

    Nor is it necessary
          that
             I should say this.

    For
         as soon
            as I see clearly
          that my sense organs
             and their activity,
       my nerve and soul processes,
          can also be known
             to me
                only through perception,
       the train
           of thought
         which
             I have outlined
            reveals itself
               in its full absurdity.

    It is quite true
         that
             I can have no percept
           without the corresponding sense organ.

    But
         just
            as little can
               I be aware
           of a sense organ
               without perception.

    From the percept
        of a table
       I can pass
          to the eye
       which sees it,
      or the nerves
          in the skin
        which touch it,
       but
          what takes place
             in these
                I can,
               in turn,
                  learn only
                     from perception.

    And
         then I
            soon notice that there is
          no trace
             of similarity
                between the process
         which
            takes place
           in the eye
               and the color
         which I perceive.

    I cannot eliminate
        my color percept
           by pointing
              to the process
           which
              takes place
            in the eye
                during this perception.

    No more can
         I rediscover
            the color
           in the nerve
               or
                  brain processes.

    I only add new percepts,
       localized
           within the organism,
       to the first percept,
          which the naïve man
        localizes
           outside his organism.

    I merely pass
        from one percept
           to another.
 
    [28] Moreover
        there is
           a gap
         in the whole argument.

    I can follow the processes
        in my organism
            up to those
               in my brain,
      even though
         my assumptions
            become more and more hypothetical
          as I
       approach the central processes
          of the brain.

    The path of external observation
        ceases
           with the process
               in my brain,
       more particularly
           with the process
         which
             I should observe
                if I
                   could deal
                      with the brain
                    using
               the instruments
                  and methods
           of physics and chemistry.

    The path of inner observation
        begins
           with the sensation,
       and continues
           up to the building
              of things
                 out of the material
                    of sensation.

    At the point
        of transition
            from brain
               process
                  to sensation,
      the path of observation
         is interrupted.

    [29] The way
        of thinking here
           described,
              known
                 as critical idealism,
            in contrast
               to the standpoint
            of naïve
           consciousness known
              as naïve realism,
      makes the mistake
          of characterizing
              the one percept
          as mental picture
        while
           taking
          the other
             in the very same sense
            as does
               the naïve realism
                  which
                     it apparently refutes.

    It wants to prove
          that percepts
              have the character
           of mental pictures
               by naïvely
                  accepting
          the percepts
             connected
           with one's own organism
               as objectively valid facts;
       and over and above
           this,
       it fails
           to see
              that it confuses two spheres
                 of observation,
       between which
          it can find no connection.
 
    [30] Critical idealism
        can refute
           naïve
              realism
                 only by itself assuming,
               in naïve-realistic fashion,
                  that one's own organism
          has objective existence.

    As soon
        as the idealist
           realizes
       that the percepts connected
          with his own
             organism
                are exactly
                   of the same nature
                      as those which naïve realism
                     assumes
            to have
                objective existence,
      he can no longer
         use
            those percepts as a safe foundation
        for his theory.

    He would have
          to regard even
             his own
                subjective organization
           as a mere complex
               of mental pictures.

    But
         this removes
            the possibility
           of regarding
               the content
                  of the perceived world
               as a product
                   of our spiritual organization.

    One would have
        to assume
           that the mental picture
              "color" was only a modification
                 of the mental picture "eye".

    So-called critical idealism
        cannot be proved
           without borrowing
               from naïve realism.

    Naive realism
        can be refuted only if,
           in another sphere,
              its own assumptions
        are accepted
           without proof
         as being valid.
 
    [31] This much,
       then,
          is certain:
       Investigation
           within the world
               of percepts
          cannot establish critical idealism,
       and consequently,
          cannot strip percepts
             of their objective character.
 
    [32] Still less
        can
           the principle
        "the perceived world
            is my mental
                  picture"
           be claimed
               as obvious
                   and needing no proof.

    Schopenhauer
        begins his chief work
           with the words:

    The world
        is my mental
              picture
       -- this is a truth
          which holds good
             for everything that lives
            and cognizes,
           though man alone
              can bring
          it
             into reflective and abstract consciousness.

    If
         he really does this,
       he has attained
           to philosophical discretion.

    It
         then becomes
              clear and certain
                 to him
                    that
                       he knows no
             sun and no earth,
       but
          only
             an eye
                 that sees a sun,
       a hand that
          feels an earth;
             that
                the world which surrounds him
              is there only
                 as mental picture,
       that is, only
           in relation
               to something else,
       to the one
          who pictures it,
       which
          is he himself.

    If any truth
          can be asserted a priori,
       it is this one,
          for it
        is the expression
           of that form
               of all possible
                  and thinkable experience
         which is more universal
            than all others,
           than time,
              space,
           or causality,
       for all
           these presuppose it.

    This whole theory is wrecked
        by the fact,
           already mentioned,
        that
       the eye
          and the hand
         are percepts
        no
       less than
          the sun
             and the earth.

    Using Schopenhauer's expressions
        in his own sense,
       we could reply:
           My eye that
          sees the sun,
       my hand that
          feels the earth,
       are my mental
          pictures just
         as much as
            the sun
               and the earth themselves.

    That with this
         the whole theory
            cancels itself,
       is clear
           without further argument.

    For only my real eye
        and
       my real hand
         could have
        the mental pictures "sun"
           and "earth"
        as modifications
            of themselves;
        the mental pictures "eye"
           and "hand" cannot have them.

    Yet
         it is only
            of these mental
               pictures
          that critical idealism
             is allowed
                to speak.
 
    [33] Critical idealism
        is totally unfitted
           to form
              an opinion
           about the relationship
               between percept
                   and mental
                  picture.

    It cannot begin
        to make the distinction,
           mentioned above,
        between
       what happens
         to the percept
            in the process
                of perception and
          what must be inherent
             in it
            prior to perception.

    We must,
       therefore,
          tackle this problem
             in another way.