Sun Tzu, or the group of authors writing under that name, produced The Art of War in the 5th century BC in the Chinese Warring States period, a time of constant low-grade military catastrophe. The book is mostly about avoiding unnecessary battles. The line about deception is usually read as a tactical note. It is closer to a full epistemology of conflict.

Deception, in Sun Tzu's sense, is not dishonesty. It is the refusal to let your opponent see the real picture. Appear weak where you are strong. Appear close when you are far. The principle extends to situations that have nothing to do with armies. Negotiations, interviews, the moment you walk into a room, the way you hold your phone. The gap between what you show and what you have is the entire playable surface of any contest.

A cat stalking a felt mouse is not acting. It is rehearsing the whole system. Low crouch. Eyes hard. Body motionless except for a single tail-tip giveaway it cannot quite suppress. The mouse is fabric. The hunt is serious. The cat is performing the maximum possible reduction of signal before committing to motion. Most of our adult lives are variations on the same practice, with softer stakes and weaker fur. Sun Tzu would have watched the cat and nodded.