From a small clue, one can see what lies ahead.
This idiom originates in Han Fei Zi (The Book of Han Fei Zi), a collection of the works by Han Fei (c. 280-233 BC), a thinker and major representative of the Legalist school in the late Warring States Period.
It is about one's ability to perceive subtle omens and foresee developing trends and the overall situation. In doing anything, one needs to gain an in-depth and accurate understanding of the evolving trends by observing both the general picture and the minor details, so as to take appropriate measures.
Addressing a training program for young officials at the Central Party School (National Academy of Governance) in March 2021, Xi Jinping urged the officials to increase their ability to see through the surface into the heart of the matter, accurately understand, effectively respond to and take the initiative in seeking change, perceive favorable opportunities, draw on strengths, and avoid weaknesses.
见微知著
“见微知著”出自《韩非子》，意为发现细微苗头，就能知道事物的演变趋势或整体状态。“微”即隐微、不明，指事物尚处于不易被察觉的潜在状态；“著”即显著、明显，指事物的本质已经充分显现或事物的发展已处于充分展开的状态。这一理念指明做任何事情，都要深刻认识、精准把握事物演变的内在规律，既要着眼全局，又要关注细微处，提前防范可能出现的问题。
2021年3月，习近平在中央党校（国家行政学院）中青年干部培训班开班式上强调，要提升见微知著的能力，透过现象看本质，准确识变、科学应变、主动求变，洞察先机、趋利避害。