The Art of War by active 6th century B.C. Sunzi

25. In making tactical dispositions, the highest pitch you can attain

is to conceal them; [The piquancy of the paradox evaporates in translation. Concealment is perhaps not so much actual invisibility (see _supra_ ยง 9) as "showing no sign" of what you mean to do, of the plans that are formed in your brain.] conceal your dispositions, and you will be safe from the prying of the subtlest spies, from the machinations of the wisest brains. [Tu Mu explains: "Though the enemy may have clever and capable officers, they will not be able to lay any plans against us."]