ver--to resist
disintegrating influences such as may arise from wars, famines, and
internal dissensions. This stability gradually rises to a maximum and
gradually declines. The degree of stability at any epoch will depend on
the fitness of some leading feature of the government to suit the
slowly altering circumstances, and that feature corresponds to the
characteristic denoted by a in the physical problem. A time at length
arrives when the stability vanishes, and the slightest shock will
overturn the government. At this stage we have reached the crisis of
a point of bifurcation, and there will then be some circumstance,
apparently quite insignificant and almost unnoticed, which is such as
to prevent the occurrence of anarchy. This circumstance or condition
is what we typified as b. Insignificant although it may seem, it has
started the government on a new career of stability by imparting to it
a new type. It grows in importance, the form of government becomes
obviously different, and its stability increases. Then in its turn this
newly acquired stability declines, and we pass on to a new crisis or
revolution. There is thus a series of "points of bifurcation" in history
at which the continuity of political history is maintained by means of
changes in the type of government. These ideas seem, to me at least, to
give a true account of the history of states, and I contend that it is
no mere fanciful analogy but a true homology, when in both realms of
thought--the physical and the political--we perceive the existence of
forms of bifurcation and of exchanges of stability.

Further than this, I would ask whether the same train of ideas does not
also apply to the evolution of animals? A species is well adapted to its
environment when the individual can withstand the shocks of famine or
the attacks and competition of other animals; it then possesses a high
degree of stability. Most of the casual variations of individuals are
indifferent, for they do not tell much either for or against success
in life; they are small oscillations which leave the type unchanged. As
circumstances change, the stability of the species may gradually dwindle
through the insufficiency of some definite quality, on which in earlier
times no such insistent demands were made. The individual animals will
then tend to fail in the struggle for life, the numbers will dwindle and
extinction may ensue. But it may be that some new variation, at first of
insignifi