12 Instinct and Intelligence 



Soddy remarks, before any object can start, 

 what we call " energy must be supplied to the 

 matter, and before it can stop this energy must 

 be taken from it." l 



At present it is an open question as to whether 

 energy possesses an atomic character; like 

 matter, we know it is conserved, and what is 

 conserved has physical existence ; in other 

 words, when energy appears it must come from 

 somewhere, and when it disappears it must go 

 somewhere. Energy has been defined as that 

 which has the power of changing the properties 

 of bodies ; it is the cause, change of condition 

 the effect, " the capacity for doing work." For 

 instance, to keep a grindstone in motion a cer- 

 tain amount of, say, muscular energy must be 

 expended to overcome the resistance opposed 

 by the air, axle bearings, etc. If a piece of steel 

 is pressed against the stone while in motion the 

 steel soon becomes warm. If a vulcanite tyre 

 be placed on the grindstone, and the rim 

 pressed with a piece of flannel electricity will be 

 developed, which can be reconverted back into 

 mechanical motion. Heat and electricity are 



1 Matter and Energy, by F. Soddy, pp. 19, 78, 91, 171. 



