14 ‘THE SHADOW OF THE WORLD'S FUTURE 
or not, except as they directly affect his food-supply. 
That we are partly dependent thereon is of course 
self-evident. But we are only beginning to study 
the physical conditions of our earth. It is already 
felt that the future of climatology is subject to a 
better knowledge of the energies which reach us from 
space. 
As regards the psychical factors which play their 
part in Man’s increase, it is perhaps fairly correct 
to assume that his ¢mtrimsic character to-day is not 
sensibly different from what it was, say, 10,000 years 
ago. Particular manifestations of human nature vary, 
but so far as history throws any light upon the subject, 
it does not appear that man’s real character has changed 
materially. = Whether the procreative urge is un- 
changing or not, we cannot say. The complex interests 
of modern life may perhaps affect it. 
A study of Man’s relatively rapid numerical growth 
recently shows that it is doubtless due to his acces- 
sions of knowledge, particularly those occurring during 
the nineteenth century. The earth is richer than he 
knew; his power to do what he desires is greater. He 
has learnt that quite recondite ideas are of practical 
value. Applied to the field of what he has discovered 
in regard to Nature, it has taught him that she is 
niggardly, often simply because he is ignorant. As 
a fact his increased knowledge has enabled him to 
exploit more successfully his complex environment. 
Much of what he formerly regarded as waste turns 
out to be of considerable value. Already this has 
borne fruit in enabling him to live a richer life; and a 
greater number can enjoy this life than ever before. 
The accumulations of knowledge are potentially stores 
of material wealth. We do not of course know the 
limit of this development. Naturally Man’s faith in 
the possibilities of his earth have become vastly greater, 
and the more sanguine spirits among those versed in