es
universal recognition. World federations and peace propaganda cannot
be effective until that principle is accepted as a working basis for
world life.

351. =The Increasing Recognition of the Principle of
Adaptation.=--This principle of adaptation has found limited
application for a long time. Starting with individuals in the family
and family groups in the clan, it extended until it included all the
members of a state in their relations to each other. Many individual
interests conflict in business and society and different opinions
clash, but all points of difference within the nation are settled by
due process of law, except when elemental passions break out in a
lynching, or a family feud is perpetuated among the hills. But war
continued to be the mode of settling international difficulties.
Military force restrained a vassal from hostile acts under the Roman
peace. But the next necessary step was for states voluntarily to
adjust their relations with one another. In some instances, even in
ancient times, local differences were buried, and small federations,
like the Achaean League of the Greeks and the Lombard League of the
Middle Ages, were formed for common defense. These have been followed
by greater alliances in modern times. But the striking instances of
real interstate progress are found in the federation of such States
as those that are included within the present United States of
America, and within the new German Empire that was formed after the
Franco-Prussian War. Sinking their differences and recognizing one
another's rights and interests, the people of such united nations have
become accustomed to a large national solidarity, and it ought not to
require much instruction or persuasion to show them that what they
have accomplished already for themselves is the correct principle for
their guidance in world affairs.

352. =International Law and Peace.=--This principle of recognizing one
another's rights and interests is the foundation of international law,
which has been modified from time to time, but which from the
publication of Hugo Grotius's _Law of War and Peace_ in the
seventeenth century slowly has bound more closely together the
civilized nations. There has come into existence a body of law for the
conduct of nations that is less complete, but commands as great
respect as the civil law of a single state. This law may be violated
by a nation in the stress of conflict, as civil law may be derided