PAPERS OF GENERAL INTEREST 67 



capable of being expended. This energy- which is ex- 

 pended by efforts comes ont of the body of the person 

 who exerts himself, and as we cannot get something out 

 of nothmg, the energy must be stored in the body of the 

 person before he can do foot-pounds of work. K the ef- 

 forts which a person makes are moderate, within the 

 ordinary meaning of that term, then the foot-pounds of 

 energy withdrawn by exercise are soon replaced by other 

 foot-pounds of energy derived from food. The condition 

 under which this results in a buildiug process is one in 

 which the amount of energy withdrawn from the system, 

 in some unit of time, as a day, week or month, shall be 

 a little less, but not much less, than the system can re- 

 plenish in the same time from the food supply. 



But it is known that by great efforts long continued 

 a man may cause his own death as a result of nothing 

 else than his o^vn exertions. This means that death is 

 caused by withdrawing from the system more than a cer- 

 tain amount of energy, and that in turn means that life 

 itself is a form of energy. We identify electricity as be- 

 ing a foiTQ of energy, even though we do not know pre- 

 cisely what this form is. In the same way we can identify 

 life as being a form of energy, even though we are im- 

 able to determine the essential nature of this form as 

 distinguished from other foiTos. 



"We have identified life as being a form of energy by 

 showing that life may be withdrawn from an individual 

 by withdrawing foot-pounds of energy, and not withdraw- 

 ing anything else. Likewise, life may be withdrawn from 

 an individual by exposure to cold which results in with- 

 drawing heat units, and not withdrawing anything else. 

 As heat units are a form of energy, we again identify 

 life as being nothing else than a foiTQ of common me- 

 chanical energy. 



By the examples given it has been shown that powers 

 are developed by exercising them, and the powers so de- 

 veloped are nothing else than stores of energy which are 

 transformable into foot-pounds of work. By referring to 

 the records of the trotting horse it is learned that those 

 horses which had their powers developed (stores of en- 



