How visible and tangible IDEAS came to have the same name if not of the same kind 140 This accounted for without supposing them of the same kind 141 OBJ. That a tangible square is liker to a visible square than 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.