21
Certainly, the American people have passed into an era of
material progress the likes of which had never been seen
before (and might not be seen again). Material progress
of the kind known during the past century may have been
the result more of peculiar circumstance and natural
abundance than of general laws. We cannot be certain
that progress of the same kind can continue unabated;
nor is it certain that the same kind of progress can be
shared by others who find themselves less well endowed.