We choose this expression not only to explain our meaning in few words, but because it represents the thing exactly, and is not so figurative as may at first appear.

The idea of wearing out in a struggle amounts in practice to A GRADUAL EXHAUSTION OF THE PHYSICAL POWERS AND OF THE WILL BY THE LONG CONTINUANCE OF EXERTION.
Now, if we want to overcome the enemy by the duration of the contest, we must content ourselves with as small objects as possible, for it is in the nature of the thing that a great end requires a greater expenditure of force than a small one; but the smallest object that we can propose to ourselves is simple passive resistance, that is a combat without any positive view.

In this way, therefore, our means attain their greatest relative value, and therefore the result is best secured.

How far now can this negative mode of proceeding be carried?
Plainly not to absolute passivity, for mere endurance would not be fighting; and the defensive is an activity by which so much of the enemy's power must be destroyed that he must give up his object.

That alone is what we aim at in each single act, and therein consists the negative nature of our object.
No doubt this negative object in its single act is not so effective as the positive object in the same direction would be, supposing it successful; but there is this difference in its favour, that it succeeds more easily than the positive, and therefore it holds out greater certainty of success; what is wanting in the efficacy of its single act must be gained through time, that is, through the duration of the contest, and therefore this negative intention, which constitutes the principle of the pure defensive, is also the natural means of overcoming the enemy by the duration of the combat, that is of wearing him out.
Here lies the origin of that difference of OFFENSIVE and DEFENSIVE, the influence of which prevails throughout the whole province of War.