From 《
战国策·
燕策》: Zhao was about to attack Yan. The strategist Su Dai told King Hui of Zhao a fable — a snipe tried to eat a clam, the clam clamped shut on its beak, neither would let go, and a passing fisherman caught them both. The moral: if Zhao and Yan exhaust each other, powerful Qin will sweep them up. Zhao called off the attack.