248 THE MEANING OF EVOLUTION 
opinion of his own based on some other ground than 
his chemistry, but so far as he is a chemist, he has 
no opinion. The chemical side of life is being very 
carefully and very fully investigated. We are cer- 
tainly being brought nearer to the borders of the 
living substance. We are rapidly gaining fuller 
knowledge of the physical and chemical processes 
which constitute life, or with which life is always as- 
sociated. If we gain this knowledge we shall be in 
better position to solve many of our other problems. 
Even then there is a problem which preceded and 
which will possibly always defy solution. How did 
life originate? Has it developed out of chemical 
and physical activities which we know as heat, light 
or electricity? If so, what were the conditions under 
which it developed? If we understand the nature of 
life, and the conditions under which it developed, we 
may be able to produce it at will. 
A few scientists may hope dimly that this will 
be attained. I suspect a great majority believe it 
to be impossible, and that the question as to whether 
life evolved upon this planet, or this planet became 
infected with life through meteoric dust from some 
other center, will forever remain an unsolved prob- 
lem. 
