The diagram theory of war by Carl von Clausewitz.
War always mixes three inseparable forces:
Passion: hatred, enmity, and the emotional drive that starts and fuels fighting. Clausewitz calls it a blind natural force, mainly rooted in the people.
Chance: friction, incomplete information, luck, and room for a commander’s judgment. Mainly the domain of the army and its leaders.
Reason: war subordinated to a political purpose. Mainly the business of government.