It's the secret of the ebbs and flows of up and down of human events.

这是人类事务起伏消长的秘密。

The interaction between yin and yang can be summed up briefly as: yin-yang conversion, mutual rooting of yin and yang, waning and waxing of yin and yang as well as unity and opposition of yin and yang.

阳的相互作用能简要概括为：阳转化，阳互根，阳消长和阳对立统。

Only much later, as a historian, did I come to understand how sharp were the ebbs and flows of presidential power - and of the quality of the men who have served in America's highest office.

直到很久以后，作为名历史学家，我才开始明白总统权力的消长有剧烈，而担任过美国最高公职的人的素质也有高低。

I mean, letting factions be created and sort of play themselves out and staying above them?

我的意思是，允许派系自行形成并逐渐消长，自己则置身事外、超然于上？

For snobberies ebb and flow ; their empire rises, declines, and falls in the most approved historical manner.

因为势利也有盛衰消长，他们的帝国也以最为公认的历史方式兴盛、衰落、消亡。