CONTENTS OF VOL. II. XI 



iu space — Cognition of space by tlie motion of a sensation — In these ways only 

 superficial extension can be cognised— Cognitions of space and of time originate 

 in parallel ways — Perception of objects external to tlie body is acquired by the 

 motor sense — Summary — Sight, like touch, originally cognises only superficial 

 extension — Perception by sight is an acquired power — Facts confirming these 

 views— Answer to objection — Perceptions due to both touch and sight — Special 

 connexion of these two senses — Cognition of space in three dimensions is due 

 to touch — Additional proof of this — Touch cognises linear magnitudes ; sight 

 cognises angular ones ; and we think more easily of the former than of the 

 latter — Words denoting the former are common : words denoting the latter are 

 technical — A being with sight only would cognise only angular magnitude — 

 Impressions of the two senses are identified iu the mind as the result of habit — 

 Account of the process — Berkeley — Quotation from M'Cosh — Difficulty about 

 instinctive actions, as a duck running to the water when it leaves the egg — 

 Explanation : these are cases of hereditary habit — Presumption that perception 

 is not a simple act, from the midtiplicity of senses — Difficulty of the subject 

 from their multiplicity and their combination — Elements involved in perception 

 enumerated — Assigameut of a sensation to its source — Cognition of space-rela- 

 tions — Perception of objects in space — Combination of impressions of touch 

 and sight^What is " the external world " external to ? — It may be extra- 

 mental, or only extra-organic — No organ of sense can perceive itself. 

 Note : — Case of a being having knowledge of space from sight only — It would 

 cognise only sm-face, and that the surface of a sphere — It would see straight 

 lines as arcs of great circles — Plane geometry would seem true to it only on 

 infinitely small surfaces — The eye cannot see a plane surface or a straight line — 

 Straight lines are seen as arcs of great circles, which intersect when produced — 

 Eeid's " Geometry of Visibles " — A Barrister's puzzle . . . Pp.117 — 132 



CHAPTEK XXXVII. 



THE RELATION OF THE MIND TO SPACE AND TIME. 



Our knowledge of time is a primary cognition : we cognise time in cognising our 

 sensations as successive — I believe space is cognised in a parallel way — Opinion 

 that space is cognised by motion only — Similarity of space and time — Both are 

 necessary — Magnitude is more naturally expressed in space than in time, though 

 number is expressed in time — Conclusion that the cognitions of the two have 

 separate origin — Is the argument relevant ? — Reason for thinking that it is — 

 Larval and mature forms of these cognitions — Reason advanced for thinking 

 that the cognition of space is from motion — Time is more inseparable from 

 our thoughts than space — I believe this is not essential to all mind, but acci- 

 dental to the human mind — Our consciousness begins with the succession of 

 sensations — Possibility of consciousness being developed in sjiace as well as 

 time — Touch, sight, and hearing minister to mind — Of these only the first two 

 give cognition of space — Hearing is the most closely connected with thought, 

 because we think iu words— Sensations of different senses may give cognition 

 of time, but only those of the same sense can give it of sjiace — Case of a mind 



