134 HABIT AND INTELLIGENCE. [chap. 



Opinion to which ]\Iill, Bain, and H. Spencer belong, think that the 

 i^ cUuisMl knowledge of space is obtained solely by moving in it ; 

 by motion and as all motion takes place in time, they infer that our 

 °" ^' knowledge of space is not a primary cognition at all, but 



derived from that of time. As I have said, I am opposed 

 to this view. In the last chapter I have stated my reasons 

 for thinking that the cognition of space is primary. Never- 

 theless there are real arguments on the other side, which 

 must be fully stated before they can be refuted. 



In approaching the question whether our knowledge of 

 space is really a primary cognition like that of time, we 

 first meet with this fact, that whether time and space are 

 Similarity considered in themselves or as objects of thought, they are 

 aucUime i^ many important respects like each other, and unlike 

 anything else. Considered in themselves, they are both 

 infinitely extended, and both infinitely divisible. Magni- 

 tude is expressible in terms either of time or of space. 

 Both have being, though neither has existence ; all things 

 exist in space, and all events occur in time. Considered 

 Both are as obiects of thought, they are both necessary; that is to 



necessary. '' , • ,t . i • tut 



say, we cannot conceive them as not bemg. We can 

 voluntarily form a mental conception of the absence of all 

 existing things, but empty space will remain : we can 

 similarly conceive the absence of all events, but time will 

 remain. We cannot conceive, by any effort of the miiid, 

 of a limit to either : we cannot conceive of a boundary in 

 any direction to space, nor can we conceive of a beginning 

 or an end to time.^ In one way, indeed, the idea of space 

 appears to cling closer to the mind than that of time ; for 

 Magnitude althoueh magnitude may be expressed in time as well 



IS more ° ° i • i p • i 



naturally as in space, we habitually think of magnitude rather as 



1 Mr. ill says it is credible to him that there may be a limit to si^ce 

 (though of course he admits that it is inconceivable), and I suppose he 

 would say the same of time. I do not agi-ee with him ; but I mention 

 this in order to point out that conceivable and credible are words and ideas 

 which ought never to be confounded ; — though it is one of the most imiior- 

 tant of all metaphysical problems, to determine how far conceivableness is 

 a test of possibility and credibility. I do not mean to charge Mr. Mill with 

 any such confusion ; on the contrary, I do not think I could name any 

 ■\vi-iter who is so free from it. 



