LAW OF CAUSATION. 393 



objects. All things which possess extension, or in 

 other words, which fill space, are subject to geome- 

 trical laws. Possessing extension, they possess figure; 

 possessing figure, they must possess some figure in 

 particular, and have all the properties which geometry 

 assigns to that figure. If one body be a sphere and 

 the other a cylinder, of equal height and diameter, 

 the one will be exactly two-thirds of the other, let 

 the nature and quality of the material be what it will. 

 Again, each body, and each point of a body, must 

 occupy some place or position among other bodies ; 

 and the position of two bodies relatively to each 

 other, of whatever nature the bodies be, may be 

 unerringly inferred from the position of each of them 

 relatively to any third body. 



In the laws of number, then, and in those of space, 

 we recognise, in the most unqualified manner, the 

 rigorous universality of which we are in quest. Those 

 laws have been in all ages the type of certainty., the 

 standard of comparison for all inferior degrees of 

 evidence. Their invariability is so perfect, that we 

 are unable even to conceive any exception to them ; 

 and philosophers have been led, although (as I have 

 endeavoured to show) erroneously, to consider their 

 evidence as lying not in experience, but in the original 

 constitution of the human intellect. If, therefore, 

 from the laws of space and number, we were able to 

 deduce uniformities of any other description, this 

 would be conclusive evidence to us that those other 

 uniformities possessed the same degree of rigorous 

 certainty. But this we cannot do. From laws of 

 space and number alone, nothing can be deduced but 

 laws of space and number. 



Of all truths relating to phenomena, the most 

 valuable to us are those which relate to the order of 



