AND ITS SELF-CONSERVATION. 9 



On the other hand, the act of sensation is either after 

 or before other such acts. That is, the act of sensation is 

 necessarily in time. 



It is evident, therefore, that both space and time are 

 necessary conditions of sensation. Without these condi- 

 tions not a single act of sensation would be possible. 



We have accordingly to consider the precise measure 

 in which these conditions determine all our sense-per- 

 ceptions. 



1. Space as a condition of sensation. The object 

 of sensation, as being extended, is necessarily in space. 

 It cannot be perceived save as occupying space. On 

 the other hand, it is perfectly easy to withdraw atten- 

 tion from all actual objects in space and thus think of 

 space as itself mere blank extension. Thus we come to 

 recognize that objectively space is at once a necessary 

 condition of the existence of bodies and a relation of 

 body to body. That is its "reality." Otherwise it is 

 mere boundless nothing. Remove bodies, and you remove 

 the one positive characteristic of space. 



But space is not merely a necessary condition of all 

 possible objects of sensation. This fact itself is dis- 

 covered only through, as being necessarily involved in, 

 the further fact that in every possible sensation, space is 

 necessarily presupposed as a fundamental condition of 

 the very act of sensation itself. For sensation is ever a 

 practical, concrete relation between a sensitive subject 

 and a space-bounded and space-occupying object. And 

 this concrete relation completed, shows us the object with 

 its space-characteristics as taken up into the conscious- 

 ness in the form of an "image," which image is, in 

 truth, just a mode of the mind, of which the outer 



