from the debtor country which used to come to it to meet interest and
redemption. It is only by shipping goods in return for goods imported
for the war that a country can keep its financial staying-power on an
even keel.

Thus the problem which a statesman who had thought out the economics
of war beforehand would have recognised as the keystone of his policy,
would have been that of diverting the activities of the country from
providing itself with comforts and amusements to turning out goods
required for war, and of doing so with the least possible friction,
the least possible alteration in the economic equilibrium of the
country, and, above all, with the least possible cost to the national
finances. We arrive at the true aspect of this problem more easily if
we leave out the question of money altogether and think of it in units
of energy. When a nation goes to war it means to say that it has to
apply so many units of energy to the business of fighting, and to
provide the fighters with all that they need. If at the beginning
of the war its utmost capacity of output was, to mention merely a
fanciful figure, a thousand million units of energy, and if it was
clear that the fighting forces of the country would need for their
proper maintenance five hundred million units of energy, then it is
clear that the nation's ordinary consumption of goods and services
would have to be reduced to the extent of five hundred millions of
units of energy, which would have to be applied to the war, that is,
assuming that its possible output remained the same.

In other words, the spending power of the citizens of the country
had to be reduced so that the industrial energy that used to go into
meeting their wants might be made available for the purposes of
fighting forces. Now what was the straightest, simplest and cleanest