Motto: Arms and the man.
Other things being equal, the remaining thing will always bring about the desired result. We reason thus in speaking of strategy or tactics, of fleets or ships, as well as of other affairs of life. What is this remaining thing?
If we create two battleships, or fleets, equal in every respect, it will necessitate that in a deadly conflict of one of them with the other, both must at the same moment, from the same causes, and in the same way, go to the bottom. But to create two ships perfectly equal is an impossibility; for although as mechanical structures made by hands they may be duplicates, yet before they can become useful there must be added the human components without which the creations would be utterly worthless. Here it is that the remaining thing comes into view. No matter if the men of the twin vessels be themselves twins, educated and trained together and always subjected to the same influences, yet will their two ships not be the same, for in the unseen movements of the one human mind there enter thoughts, ideas, conclusions beyond the conception or influence of the other human mind. We call this the personal equation.