



Produced by Col Choat.  HTML version by Al Haines.









An Essay Towards a New Theory of Vision


by

George Berkeley (1685-1753)



CONTENTS


Sect.

    1   Design
    2   Distance of itself invisible
    3   Remote distance perceived rather by experience than by sense
    4   Near distance thought to be perceived by the ANGLE of the
        OPTIC AXES
    5   Difference between this and the former manner of perceiving
        distance
    6   Also by diverging rays
    7   This depends not on experience
    8   These the common accounts, but not satisfactory
    9   Some IDEAS perceived by the mediation of others
   10   No IDEA which is not itself perceived, can be the means of
        perceiving another
   11   Distance perceived by means of some other IDEA
   12   Those lines and angles mentioned in optics, are not themselves
        perceived
   13   Hence the mind does not perceive distance by lines and angles
   14   Also because they have no real existence
   15   And because they are insufficient to explain the phenomena
   16   The IDEAS that suggest distance are, 1st, the sensation arising
        from the turn of the eyes
   17   Betwixt which and distance there is no necessary connection
   18   Scarce room for mistake in this matter
   19   No regard had to the angle of the OPTIC AXES
   20   Judgment of distance made with both eyes, the result of EXPERIENCE
   21   2ndly, Confusedness of appearance
   22   This the occasion of those judgments attributed to diverging rays
   23   Objection answered
   24   What deceives the writers of optics in this matter
   25   The cause why one IDEA may suggest another
   26   This applied to confusion and distance
   27   Thirrdly, the straining of the eye
   28   The occasions which suggest distance have in their own nature
        no relation to it
   29   A difficult case proposed by Dr. Barrow as repugnant to
        all the known theories
   30   This case contradicts a received principle in catoptrics
   31   It is shown to agree with the principles we have laid down
   32   This phenomenon illustrated
   33   It confirms the truth of the principle whereby it is explained
   34   Vision when distinct, and when confused
   35   The different effects of parallel diverging and converging rays
   36   How converging and diverging rays come to suggest the same
        distance
   37   A person extreme purblind would judge aright in the
        forementioned case
   38   Lines and angles, why useful in optics
   39   The not understanding this, a cause of mistake
   40   A query proposed, by Mr. Molyneux in his DIOPTRICS, considered
   41   One born blind would not at first have any IDEA of distance by
        sight
   42   This not agreeable to the common principles
   43   The proper objects of sight, not without the mind, nor the images
        of any thing without the mind
   44   This more fully explained
   45   In what sense we must be understood to see distance
        and external things
   46   Distance, and things placed at a distance, not otherwise perceived
        by the eye than by the ear
   47   The IDEAS of sight more apt to be confounded with the IDEAS
        of touch than those of hearing are
   48   How this comes to pass
   49   Strictly speaking, we never see and feel the same thing
   50   Objects of SIGHT twofold, mediate and immediate
   51   These hard to separate in our thoughts
   52   The received accounts of our perceiving magnitude by sight, false
   53   Magnitude perceived as immediately as distance
   54   Two kinds of sensible extension, neither of which is
        infinitely divisible
   55   The tangible magnitude of an OBJECT steady, the visible not
   56   By what means tangible magnitude is perceived by sight
   57   This further enlarged on
   58   No necessary connection between confusion or faintness
        of appearance, and small or great magnitude
   59   The tangible magnitude of an OBJECT more heeded than the visible,
        and why
   60   An instance of this
   61   Men do not measure by visible feet or inches
   62   No necessary connection between visible and tangible extension
   63   Greater visible magnitude might signify lesser tangible magnitude
   64   The judgments we make of magnitude depend altogether on experience
   65   Distance and magnitude seen as shame or anger
   66   But we are prone to think otherwise, and why
   67   The moon seems greater in the horizon than in the meridian
   68   The cause of this phenomenon assigned
   69   The horizontal moon, why greater at one time than another.
   70   The account we have given proved to be true
   71   And confirmed by the moon's appearing greater in a mist
   72   Objection answered
   73   The way wherein faintness suggests greater magnitude illustrated
   74   Appearance of the horizontal moon, why thought difficult to
        explain
   75   Attempts towards the solution of it made by several, but in vain
   76   The opinion of Dr. Wallis
