in wildernesses, forest wildernesses, sandy deserts, and frozen
lands. Men still clung closely to water and arable soil in temperate or
sub-tropical climates, they lived abundantly only in river valleys, and
all their great cities had grown upon large navigable rivers or close
to ports upon the sea. Over great areas even of this suitable land
flies and mosquitoes, armed with infection, had so far defeated human
invasion, and under their protection the virgin forests remained
untouched. Indeed, the whole world even in its most crowded districts
was filthy with flies and swarming with needless insect life to an
extent which is now almost incredible. A population map of the world
in 1950 would have followed seashore and river course so closely in
its darker shading as to give an impression that homo sapiens was an
amphibious animal. His roads and railways lay also along the lower
contours, only here and there to pierce some mountain barrier or reach
some holiday resort did they clamber above 3000 feet. And across the
ocean his traffic passed in definite lines; there were hundreds of
thousands of square miles of ocean no ship ever traversed except by
mischance.

Into the mysteries of the solid globe under his feet he had not yet
pierced for five miles, and it was still not forty years since, with
a tragic pertinacity, he had clambered to the poles of the earth. The
limitless mineral wealth of the Arctic and Antarctic circles was still
buried beneath vast accumulations of immemorial ice, and the secret
riches of the inner zones of the crust were untapped and indeed
unsuspected. The higher mountain regions were known only to a sprinkling
of guide-led climbers and the frequenters of a few gaunt hotels, and the
vast rainless belts of land that lay across the continental masses, from
Gobi to Sahara and along the backbone of America, with their perfect
air, their daily baths of blazing sunshine, their nights of cool
serenity and glowing stars, and their reservoirs of deep-lying
water, were as yet only desolations of fear and death to the common
imagination.

And now under the shock of the atomic bombs, the great masses of
population which had gathered into the enormous dingy town centres
of that period were dispossessed and scattered disastrously over the
surrounding rural areas. It was as if some brutal force, grown impatient
at last at man's blindness, had with the deliberate intention of a
rearrangement of population upon mo