《汉书·传·司马相如传下》
所以说 兴盛的时候一定要考虑衰亡，平安的时候一定要想到危险 。
故曰于兴必虑衰，安必思危。
so that prosperity should be considered when it is at its height, and danger should be on the mind when there is peace.
<s>[INST] Rewrite the following English passage in the style of Classical Chinese: so that prosperity should be considered when it is at its height, and danger should be on the mind when there is peace. [/INST] 故曰于兴必虑衰，安必思危。</s>
Rewrite the following English passage in the style of Classical Chinese: so that prosperity should be considered when it is at its height, and danger should be on the mind when there is peace.
user
故曰于兴必虑衰，安必思危。
assistant