Overcoming the Enemy's Resistance

If you want to overcome your enemy you must match your effort against his power of resistance, which can be expressed as the product of two inseparable factors, viz. the total means at his disposal and the strength of his will. The extent of the means at his disposal is a matter––though not exclusively––of figures, and should be measurable. But the strength of his will is much less easy to determine and can only be gauged approximately by the strength of the motive animating it. Assuming you arrive in this way at a reasonably accurate estimate of the enemy’s power of resistance, you can adjust your own efforts accordingly; that is, you can either increase them until they surpass the enemy’s or, if this is beyond your means, you can make your efforts as great as possible. But the enemy will do the same; competition will again result and, in pure theory, it must again force you both to extremes. - General Clausewitz, On War