Take first the question of food and population. At present 
the population of the globe is increasing at the rate of about 
20 millions a year. Most of this increase is in Russia and 
Southeast Asia. The population of Western Europe and 
the United States is nearly stationary. Meanwhile, the food 
supply of the world as a whole threatens to diminish, as a 
result of unwise methods of cultivation and destruction of 
forests. This is an explosive situation. Left to itself, it must 
lead to a food shortage and thence to a world war. Technique, 
however, makes other issues possible. 

Vital statistics in the West are dominated by medicine 
and birth control: the one diminishes the deaths, the other 
the births. The result is that the average age in the West 
increases: there is a smaller percentage of young people and 
a larger percentage of old people. Some people consider that 
this must have unfortunate results, but speaking as an old 
person, I am not sure. 

The danger of a world shortage of food may be averted 
for a time by improvements in the technique of agriculture. 
But, if population continues to increase at the present rate, 
such improvements cannot long suffice. There will then be 
two groups, one poor with an increasing population, the 
other rich with a stationary population. Such a situation can 
hardly fail to lead to world war. If there is not to be an 
endless succession of wars, population will have to become 
stationary throughout the world, and this will probably have 
to be done, in many countries, as a result of governmental 
measures. This will require an extension of scientific tech- 
nique into very intimate matters. There are, however, two 
other possibilities. War may become so destructive that, at 
any rate for a time, there is no danger of overpopulation; or 
the scientific nations may be defeated and anarchy may de- 
stroy scientific technique. 

Biology is likely to affect human life through the study of 
heredity. Without science, men have changed domestic 
animals and food plants enormously in advantageous ways. 
It may be assumed that they will change them much more, 
and much more quickly, by bringing the science of genetics 
to bear. Perhaps, even, it may become possible artificially to 
induce desirable mutations in genes. (Hitherto the only muta- 
tions that can be artificially caused are neutral or harmful.) 
In any case, it is pretty certain that scientific technique will 
very soon effect great improvements in the animals and 
plants that are useful to man. 

When such methods of modifying the congenital character 
of animals and plants have been pursued long enough to make 
their success obvious, it is probable that there will be a 
powerful movement for applying scientific methods to human 
propagation. There would at first be strong religious and 
emotional obstacles to the adoption of such a policy. But sup- 
pose (say) Russia were able to overcome these obstacles 
and to breed a race stronger, more intelligent, and more 
resistant to disease than any race of men that has hitherto 
existed, and suppose the other nations perceived that unless 
they followed suit they would be defeated in war, then either 
the other nations would voluntarily forgo their prejudices, or, 
after defeat, they would be compelled to forgo them. Any 
scientific technique, however beastly, is bound to spread if 
it is useful in war— until such time as men decide that they have 
had enough of war and will henceforth live in peace. As 
that day does not seem to be at hand, scientific breeding of 
human beings must be expected to come about. I shall return 
to this subject in a later chapter. 

Physiology and psychology afford fields for scientific tech- 
nique which still await development. Two great men, Pavlov 
and Freud, have laid the foundation. I do not accept the view 
that they are in any essential conflict, but what structure 
will be built on their foundations is still in doubt. 

I think the subject which will be of most importance polit- 
ically is mass psychology. Mass psychology is, scientifically 
speaking, not a very advanced study, and so far its professors 
have not been in universities: they have been advertisers, 
politicians, and, above all, dictators. This study is immensely 
useful to practical men, whether they wish to become rich 
or to acquire the government. It is, of course, as a science, 
founded upon individual psychology, but hitherto it has 
employed rule-of-thumb methods which were based upon a 
kind of intuitive common sense. Its importance has been 
enormously increased by the growth of modern methods of 
propaganda. Of these the most influential is what is called 
"education." Religion plays a part, though a diminishing one; 
the press, the cinema, and the radio play an increasing part. 

What is essential in mass psychology is the art of per- 
suasion. If you compare a speech of Hitler's with a speech of 
(say) Edmund Burke, you will see what strides have been 
made in the art since the eighteenth century. What went 
wrong formerly was that people had read in books that man 
is a rational animal, and framed their arguments on this 
hypothesis. We now know that limelight and a brass band 
do more to persuade than can be done by the most elegant 
train of syllogisms. It may be hoped that in time anybody will 
be able to persuade anybody of anything if he can catch 
the patient young and is provided by the State with money 
and equipment.