74 THE REIGN OF LAW. 



never vary? Or, if there are variations, how 

 comes it that these are always found to follow 

 some other rules as exact and as invariable as the 

 first ? 



And as there can be no better example of what 

 Law is, so also there can be no better example of 

 what it is not — than the Law of Gravitation. The 

 discovery of it was probably the highest exercise 

 of pure intellect through which the human mind 

 has found its way. It is the most universal 

 physical law which is known to us, for it prevails, 

 apparently, through all Space. Yet of the Force 

 of Gravitation all we know is, that it is a 

 force of attraction operating between all the 

 particles of matter in the exact measure which 

 was ascertained by Newton, — that is — "directly 

 as the mass, and inversely as the square of the 

 distance." This is the Law. But it affords no 

 sort of explanation of itself. What is the cause 

 of this Force — what is its source — what are the 

 media of its operation — how is the exact uni- 

 formity of its proportions maintained ? — these are 

 questions which it is impossible not to ask, but 

 which it is quite as impossible to answer. Sir 



