The Spatial Conception op the Blind. 21 
Now it must not be supposed that the blind gain through this 
aural perception very definite information as to space relations. They 
can to some extent judge the distance of an object away from them 
and its heighth, if this is not greater than their own; distinguish a 
continuous wall from a broken one, best illustrated by different 
kinds of fences, whether solid or made of slats. They gain a com- 
parative idea of the thickness of trees or similar objects which they 
pass. Recesses in a continuous wall, such as are afforded by doors 
and windows can be detected, and sometimes a change of material 
in such a surface can be perceived, thus when a wooden door occurs 
in a plastered wall, while the plane of the door is not appreciably 
back of that of the wall. 
The result then is, that the only accurate *space-perception of the 
blind is had through touch, and primarily through touch involved 
in clasping an object in the hand, or holding it in both hands. This 
is a most important distinction from sight, which, as already men- 
tioned, is not bound to such close range. The act of seeing, further- 
more, is almost automatic, while an act of touch nearly always re- 
quires a distinct volition. It follows, therefore, that a seeing person 
is continually led to have spatial images in the mind, while this is 
not the case with the blind person. The latter, in his association 
with the seeing, who think and speak in terms of sight, is continually 
confronted with ideas from this source. He can however only in 
few instances investigate matters by touch, indeed this would require 
a great expenditure of time and physical exertion, not to mention 
the fact that many objects are inaccessible to him, either on account 
of their position, or on acocunt of their delicacy or minuteness. 
The field of his experience being thus limited, the blind person 
must resort to other means, if he is to gain space ideas beyond the 
most crude. In the first place, when an object presents itself to the 
touch, and is of dimensions sufficiently small to permit its being very 
nearly covered by the clasp of both hands, a rough idea of its form 
is had, which must be perfected by an analysis of its various parts, 
expressed in the words, feeling of it. In this way a pretty clear con- 
ception of its spatial character is formed. This process is employed 
also, when the object permits of beingj touched at its extremes by 
both hands simultaneosuly with extended arms. 
It seems that few blind persons get beyond this, and hence their 
conceptions are always of objects in their natural size. One person 
who was given sight by the removal of congenital cataract expressed 
surprise at being shown the picture of a human face in a locket, that 
this could be put into so small a space. 
Turning now to that small class of individuals whose power of 
