an interest, have been made from the point of view
of the fundamental human traits involved, notably Thomas' article on
_The Gaming Instinct_, Groos's chapter on "Fighting Play," in his _Play
of Man_, and G. T. W. Patrick's _Psychology of Relaxation_, in which the
theory of catharsis, familiar since Aristotle, is employed to explain
play, laughter, profanity, the drink habit, and war.

Original materials exist in abundance for the study of feud, litigation,
and war. No attempt seems to have been made to study feud and litigation
comparatively, as Westermarck has studied marriage institutions.
Something has indeed been done in this direction with the subject of
war, notably by Letourneau in France and by Frobenius in Germany.
Sumner's notable essay on _War_ is likewise an important contribution to
the subject. The literature upon war, however, is so voluminous and so
important that it will be discussed later, separately, and in greater
detail.

Quite as interesting and important as that of war is the natural history
of discussion, including under that term political and religious
controversy and social agitation, already referred to as impersonal or
secondary conflict.

The history of discussion, however, is the history of freedom--freedom,
at any rate, of thought and of speech. It is only when peace and
freedom have been established that discussion is practicable or
possible. A number of histories have been written in recent years
describing the rise of rationalism, as it is called, and the role of
discussion and agitation in social life. Draper's _History of the
Intellectual Development of Europe_ and Lecky's _History of the Rise and
Influence of the Spirit of Rationalism in Europe_ are among the earlier
works in this field. Robertson's _History of Free Thought_ is mainly a
survey of religious skepticism but contains important and suggestive
references to the natural processes by which abstract thought has arisen
out of the cultural contacts and conflicts among peoples, which conquest
and commerce have brought into the same universe of discourse. What we
seem to have in these works are materials for the study of the communal
processes through which thought is formulated. Once formulated it
becomes a permanent factor in the life of the group. The role of
discussion in the communal process will be considered later in
connection with the newspaper, the press agent, propaganda, and the
various factors and mechanisms det