more resolute must we be in seeking points of departure from which we can
begin to lay a course, keeping always an eye open for the accidents that
will beset us, and being always alive to their deflecting influences. And
this is just what the theoretical study of strategy can do. It can at least
determine the normal. By careful collation of past events it becomes clear
that certain lines of conduct tend normally to produce certain effects;
that wars tend to take certain forms each with a marked idiosyncrasy; that
these forms are normally related to the object of the war and to its value
to one or both belligerents; that a system of operations which suits one
form may not be that best suited to another. We can even go further. By
pursuing an historical and comparative method we can detect that even the
human factor is not quite indeterminable. We can assert that certain
situations will normally produce, whether in ourselves or in our
adversaries, certain moral states on which we may calculate.

Having determined the normal, we are at once in a stronger position. Any
proposal can be compared with it, and we can proceed to discuss clearly the
weight of the factors which prompt us to depart from the normal. Every case
must be judged on its merits, but without a normal to work from we cannot
form any real judgment at all; we can only guess. Every case will assuredly
depart from the normal to a greater or less extent, and it is equally
certain that the greatest successes in war have been the boldest departures
from the normal. But for the most part they have been departures made with
open eyes by geniuses who could perceive in the accidents of the case a
just reason for the departure.

Take an analogous example, and the province of strategical theory becomes
clear at once. Navigation and the parts of seamanship that belong to it
have to deal with phenomena as varied and unreliable as those of the
conduct of war. Together they form an art which depends quite as much as