208 PSYCHOLOGY. 



turn round mentally, and in doing so tlie front space van- 

 ishes. But in this, as in the other things of which we have 

 been talking, individuals differ widely. Some, in imagin- 

 ing a room, can think of all its six surfaces at once. Others 

 mentally turn round, or, at least, imagine the room in sev- 

 eral successive and mutually exclusive acts (cf. p. 54, above). 



Sir William Hamilton, and J. S. Mill after him, have 

 quoted apjDro^dngly an opinion of Platner (an eighteenth- 

 century philosopher) regarding the space-perceptions of 

 the blind. Platner says : 



"The attentive observation of a person born blind . . . has con- 

 vinced me that the sense of tonch by itself is altogether incompetent to 

 afford us the representation of extension and space. ... In fact, to 

 those born blind, time serves instead of space. Vicinity and distance 

 mean in their mouths nothing more than the shorter or longer time 

 . . . necessary to attain from some one feeling to some other." 



After my own observation of blind people, I should 

 hardly have considered this as anything but an eccentric 

 opinion, worthy to pair off with that other belief that color 

 is jDrimitively seen without extent, had it not been for the 

 remarkable Essay on Tactile and Visual Space by M. Ch. 

 Dunan, which appeared in the Eevue Philosophique for 

 1888. This author quotes * three very competent witnesses, 

 all officials in institutions for the blind [it does not appear 

 from the text that more than one of them was blind him- 

 self], who say that blind people only live in time. M. 

 Dunan himself does not share exactly this belief, but he 

 insists that the blind man's and the seeing man's represen- 

 tation of space have absolutely naught in common, and that 

 we are deceived into believing that what they mean by 

 space is analogous to what we mean, by the fact that so many 

 of them are but semi-blind and still think in visual terms, 

 and from the farther fact that they all toR in visual terms 

 just like ourselves. But on examining M. Dunan's reasons 

 one finds that they all rest on the groundless logical as- 

 sumption that the perception of a geometrical form which 

 we get with our eyes, and that which a blind man gets with 



*Vol. XXV. pp. 357-8. 



