still water runs deep, 我还特意写过一首曲子. 这个短语

Still waters run deep is a proverb of Latin origin now commonly taken to mean that

a placid exterior hides a passionate or subtle nature

描述韬光养晦的表层意思很贴切. 对韬光养晦的隐含的野心, 则没有点出. 

不过很不错了.