38 LIFE: ITS ORIGIN AND NATURE 
The theory which I am inclined to defend is 
briefly the following: The human body does 
not resemble the steam engine as much as it 
does the electric motor, which at certain times 
is recharged by energy from without. During 
the hours of rest and sleep, the human body is 
similarly charged by some cosmic energy which 
flows into it at such times. This energy is 
merely expended in the various bodily and 
mental activities, but the source of the energy 
is not the food, which only supplies the body 
with a certain amount of heat and replaces 
broken-down tissue. The more tissue which is 
broken down, in work, the more must be re¬ 
placed; consequently a greater amount of food 
must be consumed in order to repair this waste. 
There is, therefore, an equivalence; but this 
equivalence is not that of cause and effect. If 
the strings of a musical instrument were self¬ 
repairing, we might perhaps be inclined to 
think that the material which fed the strings 
was the cause of the music, since in that case 
some measure of the waste would probably be 
discoverable in the debris emitted; and we 
might imagine that the debris was the measure 
of the music, while what it really was was the 
measure of the waste of the strings when they 
were made the instrument of music. If a spade 
is used in digging, the spade wastes in pro¬ 
portion to every spadeful of earth it is made to 
lift. The more it digs, the more it wastes. If 
we could arrange that a stream of fine steel 
particles flowed into the spade, to replace the 
waste caused by each act of digging, we might 
perhaps come to think that these fine steel par¬ 
ticles were the cause of the digging—especially 
