to a visible circle
142 ANS. That a visible square is fitter than a visible circle,
to represent a tangible square
143 But it doth not hence follow, that a visible square
is like a tangible square
144 Why we are more apt to confound visible with tangible IDEAS,
than other signs with the things signified
145 Several other reasons hereof, assigned
146 Reluctancy in rejecting any opinion, no argument of its truth
147 Proper objects of vision the language of nature
148 In it there is much admirable, and deserving our attention
149 Question proposed, concerning the object of geometry
150 At first view we are apt to think visible extension the object
of geometry
151 Visible extension shown not to be the object of geometry
152 Words may as well be thought the object of geometry,
as visible extension
153 It is proposed to inquire, what progress an intelligence that
could see, but not feel, might make in geometry
154 He cannot understand those parts which relate to solids, and
their surfaces, and lines generated by their section
155 Nor even the elements of plane geometry
156 The proper objects of sight incapable of being managed as
geometrical figures
157 The opinion of those who hold plane figures to be the immediate
objects of sight, considered
158 Planes no more the immediate objects of sight, than solids
159 Difficult to enter precisely into the thoughts of the
above-mentioned intelligence
160 The object of geometry, its not being sufficiently understood,
cause of difficulty, and useless labour in that science

AN ESSAY TOWARDS A NEW THEORY OF VISION

1. My design is to show the manner wherein we perceive by sight the
distance, magnitude, and situation of OBJECTS. Also to consider the
difference there is betwixt the IDEAS of sight and touch, and whether
there be any IDEA common to both senses.

2. It is, I think, agreed by all that DISTANCE, of itself and
immediately, cannot be seen. For DISTANCE being a Line directed end-wise
to the eye, it projects only one point in the fund of the eye, which
point remains invariably the same, whether the distance be longer or
shorter.

3. I find it also acknowledged that the estimate we make of the distance
of OBJECTS considerably remote is rather an act of judgment grounded on
EXPERIENCE than of SENSE. F