Spies are a most important element in water, because on them depends an army's ability to move.
Sun TzuTo ... not prepare is the greatest of crimes; to be prepared beforehand for any contingency is the greatest of virtues.
Sun TzuTo see victory only when it is within the ken of the common herd is not the acme of excellence.
Sun TzuWhen you do battle, even if you are winning, if you continue for a long time it will dull your forces and blunt you edge...If you keep your armies out in the field for a long time, your supplies will be insufficient. Transportation of provisions itself consumes 20 times the amount transported.
Sun Tzu