贤主愈大愈惧，愈强愈恐。故贤主于安思危，于达思穷，于得思丧。《周书》曰：“若临深渊，若履薄冰。”以言慎事也。 --《吕氏春秋-慎大》

For a wise king, the bigger and stronger his country grows, the more worried he becomes. So the wise king considers how to overcome crisis while in times of peace, how to deal with poverty while the country enjoys prosperity, how to stop losses while he is gaining a lot. The 《Book of Zhou》 says, "We should govern the country as if approaching an abyss or treading on thin ice of a deep river". It means one should be extremely cautious and prudent in dealing with worldly matters.