the evolution began and ended, and the nature of the
change which it effected. All evolutions present common features which
enable them to be divided into stages. Every habit (usage or
institution) begins by being the spontaneous act of several individuals;
when others imitate them it becomes a usage. Similarly social functions
are in the first instance performed by persons who undertake them
spontaneously, when these persons are recognised by others they acquire
an official status. This is the first stage; individual initiative
followed by general imitation and recognition. The usage becomes
traditional and is transformed into an obligatory custom or rule; the
persons acquire a permanent status and are invested with powers of
material or moral constraint. This is the stage of tradition and
authority; very often it is the last stage, and continues till the
society is destroyed. The usage is relaxed, the rules are violated, the
persons in authority cease to be obeyed; this is the stage of revolt and
decomposition. Finally, in certain civilised societies, the rule is
criticised, the persons in authority are censured, by the action of a
part of the subjects a rational change is effected in the composition of
the governing body, which is subjected to supervision; this is the stage
of reform and of checks.

IV. In the case of unique facts we cannot expect to bring several
together under a common formula, for the nature of these facts is to
occur but once. However, it is imperatively necessary to abridge, we
cannot preserve all the acts of all the members of an assembly or of all
the officers of a state. Many individuals and many facts must be
sacrificed.

How are we to choose? Personal tastes and patriotism give rise to
preferences for congenial characters and for local events; but the only
principle of selection which can be employed by all historians in common
is that which is based on the part played in the evolution of human
affairs. We ought to retain those persons and those events which have
visibly influenced the course of an evolution. We may recognise them by
our inability to describe the evolution without mentioning them. The men
are those who have modified the state of a society either by the
creation or the introduction of a habit (artists, men of science,
inventors, founders, apostles), or as directors of a movement, heads of
states, of parties, of armies. The events are those which have brought
about change