After a victorious military campaign, a general returns home to glory and prosperity. The king rewards him and claims that all enemies will be intimidated by the general. From then on, the general no longer practices martial arts. He eats, drinks, lives the glamorous life, and doesn't bother anymore with sharpening his weapons. When the enemy one day returns, his own arrogance leads to his defeat and eventually to the downfall of the whole nation.

(Source: Wikipedia)