436 THE PRINCIPLES OF SCIENCE. 



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 inevitably presents itself. A 

 natural law like that of gravitation expresses a certain 

 uniformity in the mode of action of agents submitted to 

 it, and this uniformity produces, as we have seen, certain 

 geometrical restrictions upon the effects which those 

 agents may produce. But there are other forces and 

 laws besides those of gravity. Pne force may override 

 another, and two laws may each be obeyed and may 

 each disguise the action of the other. Jin the intimate 

 constitution of matter there may be hidden springs of 

 force 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 forces 

 of the loadstone does not the less obey the law of gravity^) 

 A plant also gravitates downwards as regards every con- 

 stituent cell or fibre, and yet it persists in growing 

 upwards.] Life altogether is an exception to the simple 

 phenomena of mineral substances, not in the sense of 

 disproving those laws, but in that of superadding forces 

 of new and inexplicable character. Doubtless no law of 

 chemistry is broken by the action of the nervous cells, 

 and no law of physics by the pulses of the nervous 



