a thousand other facts of history also indicate, that civilization
and the peaceful arts contribute to the longevity of nations--not only
by promoting personal comfort, and by removing causes of internal
strife, and thus enabling large bodies of people to dwell together
happily, but also by increasing their military power. Every nation
which has achieved greatness has cultivated assiduously both the
arts of peace and the arts of war. Every nation which has long
maintained that greatness has done so by maintaining the policy
by which she acquired it. _Every nation that has attained and then
lost greatness, has lost it by losing the proper balance between the
military and the peaceful arts; never by exalting unduly the military,
but always by neglecting them, and thereby becoming vulnerable to
attack_.

In other words, the history of every great nation that has declined
shows three periods, the rise, the table-land of greatness, and
the decline. During the rise, the military arts hold sway; on the
table-land, the arts of peace and war are fairly balanced; during
the decline the peaceful arts hold sway. _Facilis descensus Averni_.
The rise is accomplished by expending energy, for which accomplishment
the possession of energy is the first necessity; the height of
the table-land attained represents the amount of energy expended;
the length of time that the nation maintains itself upon this
table-land, before starting on the inevitable descent therefrom,
represents her staying power and constitutes her longevity as a
great nation.

How long shall any nation stay upon the table-land? As long as
she continues to adapt her life wisely to her environment; as long
as she continues to be as wise as she was while climbing up; for