Sun-tzu expressed this idea differently: what you aim for in strategy, he said, is shih, a position of potential force—the position of a boulder perched precariously on a hilltop, say, or of a bowstring stretched taut. A tap on the boulder, the release of the bowstring, and potential force is violently unleashed. The boulder or arrow can go in any direction; it is geared to the actions of the enemy.