742 THE PRINCIPLES OF SCIENCE. [CHAP. 



of gravity, when it holds true, is no restriction on the 

 distribution of force. That law is a geometrical law, and 

 it would in many cases be mathematically impossible, as 

 far as we can see, that the force of gravity acting on one 

 particle should be small while that on a neighbouring 

 particle is great. "We cannot conceive that even Omni- 

 potent Power should make the angles of a triangle greater 

 than two right angles. The primary laws of thought and 

 the fundamental notions of the mathematical sciences do 

 not seem to admit of error or alteration. Into the meta- 

 physical origin and meaning of the apparent necessity 

 attaching to such laws I have not attempted to inquire in 

 this work, and it is not requisite for my' present purpose. 

 If the law of gravity were the only law of nature and the 

 Creator had chosen to render all matter obedient to that 

 law, there would doubtless be restrictions upon the effects 

 derivable from any one distribution of matter. 



Hierarchy of Natural Laws. 



A further consideration presents itself. A natural law 

 like that of gravity expresses a certain uniformity in the 

 action of agents submitted to it, and this produces, as we 

 have seen, certain geometrical restrictions upon the effects 

 which those agents may produce. But there are other 

 forces and laws besides gravity. One force may override 

 another, and two laws may each be obeyed and may each 

 disguise the action of the other. In the intimate constitu- 

 tion of matter there may be hidden springs which, while 

 acting in accordance with their own fixed laws, may lead 

 to sudden and unexpected changes. So at least it has 

 been found from time to time in the past, and so there 

 is every reason to believe it will be found in the future. 

 To the ancients it seemed incredible that one lifeless stone 

 could make another leap towards it. A piece of iron 

 while it obeys the magnetic force of the loadstone does 

 not the less obey the law of gravity. A plant gravitates 

 downwards as regards every constituent cell or fibre, and 

 yet; it persists in growing upwards. Life is altogether an 

 exception to the simpler phenomena of mineral substances, 

 not in the sense of disproving those laws, but in superadding 

 foir.es of new and inexplicable character. Doubtless no 



