irectly neutralize a certain amount
of exportation of capital.

_Effects experienced within Economic Society from Interchanges with
the Environing Area._--The introduction of improved methods of
production within the central area usually calls for an expenditure of
capital there, and this is largely furnished from the net profits from
previous economies in production, and will, in its turn, furnish net
profits that will convert themselves into the capital needed for
applying future inventions. The study of the causes of an increase of
capital, as well as of each of the generic changes that are going on
within the center we defer for later chapters; but at present we need
to know that the changes going on within what we define as economic
society are affected by the intercourse which that society maintains
with its environment. Immigration across the outer boundary of the
general division enhances the rapidity of growth of the population
within it, while emigration reduces it. Exporting capital in itself
reduces the rate of accumulation at home, and importing increases it.
Introducing into foreign regions economical methods in use at home,
modifies the trade which goes on between the great areas, and there
is a perpetual rivalry between the direct and the indirect process of
obtaining goods at home. When a unit of labor can directly make more
of _A'''_ than it can procure by making _A_ and exchanging it abroad
for _A'''_, the manufacture of _A'''_ is legitimate and profitable,
but when the unit of labor can procure more of _A'''_ by the indirect
process in which an exchange with a foreign region intervenes, static
law requires that this indirect process be resorted to. We should make
_A_ and buy _A'''_ in order to get the most of the latter commodity.
This is the essence of the time-honored argument for freedom of trade,
but the conclusion to which it leads is modified by a consideration of
further dynamic influences which will, in due time, be presented.

_How we may get Valid Results by Studying only a Part of the
World._--It is entirely possible to study by themselves the activities
of such a part of the world, and we will therefore draw a line of
demarcation about the countries which constitute the economic center
of it, and thus include an area within which economic causes produce
speedy effects. Each part of this area quickly responds to influences
that originate in any other part. If the steel mills in America ma