《商君书·立本》
所以强大的国家一定要使他的军队具备勇敢顽强地战斗意志，有了斗志就能尽全力打仗，拼尽了全力打仗，军队就会有无穷的潜力，这样的军队才能无敌于天下。
故曰：强者必刚斗其意，斗则力尽，力尽则备，是故无敌于海内。
Therefore, a powerful country must ensure that its army has the will to fight bravely and tenaciously. With fighting spirit, they can fight with all their strength. With all their strength, the army will have infinite potential, and such an army will be invincible in the world.