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